Chapter III: Appendix (2)

In the first place we lack in America the great stimulus to mental progress already referred to, international jealousy and emulation. In this respect we are situated very much like the Chinese, but if anything less favorably. We practically own the continent. We have no fear of Tartar invasions from the west nor Japanese from the north east. The Canadians are of identical race with ourselves, and are almost certain to become identical in nationality with us. We are accustomed to boast ourselves of this, and to look with great satisfaction on our isolated position among nations. But our self-gratulation must be greatly tempered by the reflection that such isolation is only beneficial so long as we can maintain our ideals without external stimulus. And this is something that few nations have so far been able to accomplish. It is true, however, that the Atlantic ocean is not so wide as it was formerly, and we are truly one of the family of the Indo-European nations. But we will miss the effect of the daily stimulus which they afford each other, and the daily contact which transmits so much from man to man.

What is our present intellectual rank among these nations to-day; meaning by this our status in actual production of intellectual work, and leaving aside history? Without any great competence to speak on many branches of such work, I may be not far from correct; if I summarise as follows: In music and sculpture unproductive; in painting and literature (as an art) good, but weak in quantity in comparison with our population. In sciences, feeble in many branches, but very productive in some others. I refer to pure science. In applied science we stand high. In philosophy as a nation, weak.

But we have the future before us. If there is a demand for the products of pure thought in this country, the supply will come. Much may be expected of our race. We will hope that the demand will grow, for at present it is not as large as it ought to be. It is of course easy for thought to “run in accustomed channels,” and many people there are in this as in all other countries, who believe that sufficient is already known, and that he who would disturb current opinions is a “disturber of the peace.” Strange as it may seem, in this comparatively new country we have one special inducement to this habit of mind. This is to be found in our political system, which requires an unhesitating submission to the will of the majority.

* * * * *

Here is our second danger. We are apt to confuse mental submission with physical submission. Physical submission to the will of the majority is generally necessary for physical reasons, with which we are all familiar. Ballots are simply a peaceful representation of bullets, and we anticipate the submission to the latter by submission to the former. But the mind should be free. Current or popular opinions are not always correct. In fact if they were, reform or progress would be unnecessary. A proposal for change always begins with a minority, and much time may often elapse before such change becomes acceptable to the majority. Before the majority accepts a new step of progress the progressive idea cannot govern physically. It must be content to be unpopular for a greater or less time. Now the politician naturally dreads unpopularity, for it is political death. And just in proportion as we are politicians do we share in this unfortunate mental attitude. And how many Americans are not politicians? It is the prevalent ethical disease of Americans. If it becomes general, the progress of this country is ended, and her fate among nations is sealed. Her manhood is gone, and woman may well feel her hand itch to

“Defeat their dirty tricks
Confound their politics.”

The prevalence of the habit of submission to what we know to be wrong in this country is simply detestable. Herbert Spencer has given us some excellent advice on this subject, and we will do well to heed it. The habit extends all the way through political, scientific, and domestic economy. The unpopularity of the reformer is expressed in the term “kicker,” which is applied to him among the lower classes in this country. As one of its advocates once said to me, it is the “American System,” and there was a strong element of truth in his assertion. With such people, criticism is identical with quarrelling, for they cannot conceive of any motive for endeavoring to reform some abuse or correct some error, but personal rancor. Such an attitude is a sure mark of intellectual mediocrity and ethical incapacity, and it infinitely increases the pains of the reformer, and readily converts him into a martyr. However, there are a good many men left in this country, and there are agencies at work which will probably keep up the supply.

In the absence of compulsion in the form of external or civil wars and other disasters, the churches are doing a good work in keeping ideals before the people, and in inviting corresponding practical life. It is true that their efforts are more or less retarded by the insistence on erroneous and even absurd opinions about some things, but they do infinite service in teaching that “man shall not live by bread alone,” nor by the mere display of physical possessions. They teach that there are ideals of truth and beauty better worth living for, and that the mind is the greater part of man. It is the churches which make the majority of scientists and philosophers, as they formerly did of painters. Then let the churches flourish. Like the nations of Europe, their emulations and antagonisms bring out the truth. The Presbyterians have to solve the knotty questions of biblical inspiration and divine order. The Methodists will have to study the nature and value of human emotions. The Friends will know what is to be known of immediate divine influence. The Catholics have learned how to restrain in some measure the most thoughtless of mankind. The Unitarians and Ethical Culturists are proving that man may retain and live up to high ideals without much or any theology. So long as there is no philosophy or none to speak of in America, the evolution of thought will come from the conflicts of the theologies; a peaceful war which is far less wasteful than physical wars. Theology has been generally in Europe the parent of philosophy, and so it will be here. From the various stages and conditions of the agitation will spring science and art. By this method man is led into progress by measures which involve the best attributes of his nature, instead of being driven by appeals to his lower motives, or by physical force. In this progress moral courage is not lost, but it is developed; and criticism is truth’s best weapon, and is not a cause of offense. That this progress in the churches is real, is proven by our Woodrow, McQueary, Briggs, and others, and it will go on as long as the love of truth and moral courage exist in those organisations.

It is interesting to remember that this struggle of opinions has passed through the same stages in Europe wherever the love of truth has had an abiding place. This is especially true of Germany, where also philosophy has had so large a development in relatively modern times. But we need something more than opinions to counteract the dangers which threaten earnestness of character in this country, which I have pointed out. Active organisations are necessary, which shall resist tendencies to crystallisation from both sides. Non-theological people must be stimulated to maintain ethical ideals; and theological people must be restrained from smothering them under useless and obstructive dogmas and practices. It is too true that while some theological dogmas include high ethical ideals, other dogmas discredit them by deriving them from incredible sources, and seeking to sustain them by incredible sanctions. Where such dogmas are sincerely held, true thought is suppressed, knowledge makes slow progress, and ethical life is more difficult.

As already remarked, we cannot yet claim to be, as a nation, distinguished for profound thinking on the subjects of highest human interest; nor yet are we the most thoughtless. Ignorance of the possibilities of mind is not so general as in some parts of Europe, but it is greater than in others. Material objects and interests occupy almost as exclusively the minds of the majority of our citizens whom we are accustomed to consider “intelligent,” as among the unintelligent. Hence our proneness to boast of our material greatness, instead of our intellectual conquests. Hence that weakest of all forms of self-praise, the publication of the dimensions of our country and its rapid growth, as though these were indications of our superiority as a people or as a race. This is repeated _ad nauseam_, while our real merits, our contributions to the stock of the world’s progress in thought, knowledge, and mental power, are passed by in silence. Our newspaper press reflects this state of affairs, since they generally think it their best policy to follow rather than lead public opinion. There are, however, noteworthy exceptions to this character of the press both in the east and the west, which we owe to the superiority of the men who edit and direct them.

In the conduct of our schools and of our scientific organisations, we have a corresponding exhibition of mediocrity or worse, with a few noble and distinguished exceptions. A mere interest in education and research does not confer competency to direct and sustain them; yet an interest in such matters is generally the only qualification demanded of the directors of such institutions, provided they understand how to buy, sell, and invest money. It is to be hoped that this state of affairs will some day pass away, and that men who are influential in such matters will some time know enough themselves to distinguish between the false and the true, and between men of ability and adventurers who are after the money and position with which our institutions of learning and our scientific enterprises can endow them. This reform will progress exactly in proportion as it is understood how much human happiness depends on true research and on correct thinking, and how little on revelation and on ancient dogma.

It is not, I repeat, sufficiently understood, how much human conduct depends on correct thinking. How much financial dishonesty would be averted by a rational thought as to the inevitable consequences? How much social irregularity would be prevented by a similar treatment of the subject? How much hatred and wasteful antagonism would the world lack, if the ordinary conditions of living were understood and acted on! So the cultivation of the rational mind is of incalculable importance, and if we wish to prosper as a nation we must bend our energies to the pleasant task this problem presents to us. Neglect of our mental powers means degeneracy and decay; while their cultivation means power and happiness. Wealth, except as a means of attaining this end, after physical necessities are supplied, is simply useless.

E. D. COPE.

MENTAL MUMMIES.

If we should name the most important factor in the changes which have gradually widened the contrast between modern science and the scholasticism of the Middle Ages, we might define it as a “progressive recognition of hereditary influences.”

There was a time when each individual of the human race was considered a separate accident, called into existence by an act of unlimited, arbitrary power, and apt to be as suddenly changed, even unto a complete inversion of his former moral being, by a merciful, or revengeful, caprice of the same power.

Biology has since taught us to apply the doctrine of evolution to the problems of our own moral and physical nature, to trace the tendencies of bygone times to their effects in the present age, to consider individuals the outcome of a long series of precedent influences, and to recognise the truth that the length of those influences is proportioned to the persistence of the result.

Intelligent statesmen were the first to appreciate the practical value of those facts. The advisers of Alexander II. did not waste their time in a hopeless attempt to convert the freedom-worshipping natives of the Caucasus into devotees of Muscovite despotism, but at once confronted them with the alternative of exile or death. Our Indian commissioners early realised the impossibility of turning the descendants of a long ancestry of deer-hunters into tillers of the soil, and transferred the survivors of the long race-war to a territory where they could for better or worse, indulge their incurable penchant. The Groot Fontein penitentiary of the Transvaal Republic became the grave of so many Caffirs that the managers at last abandoned the plan of inuring nomads to the restraints of sedentary occupation, and saved the lives, if not the souls of their convicts by sending them about in chain-gangs to mend the irrigation ditches of the border settlements.

Hereditary influences cannot be obliterated by force of rhetoric or of government edicts and it would solve many riddles if we would apply that principle to phenomena of ethical and religious evolution. How else shall we explain the fact that in less than sixty years the doctrine of Protestantism spread from central Germany to the highland hamlets of Scotland and Scandinavia, while in Spain, Portugal, and Italy a very decided progress in general intelligence has failed to lead to a similar result? How shall we account for the success of Christian missionaries in Tasmania and Otaheiti and their utter failure in Burmah and Hindostan? How for the persecution-proof vitality of Judaism, the ready collapse of Mormonism, or the revival of crass mystic delusions in the midst of our realistic civilisation?

There is no doubt that the average Spanish sailor, or village-shopkeeper of to-day possesses a larger stock of general information than the average Brunswick school-teacher of the sixteenth century. Yet one of the least learned of those school-teachers could, by instinct, sufficiently appreciate the significance of the Protestant revolt to celebrate its triumph by a big bonfire and what our western friends would, call a “grand war-dance,” on a height near the little town of Wolfenbüttel. Why does Pedro Gonzales still cross himself at the mention of a heretic, while Peter Jansen would as soon return to the pig-sty hovels of the mediæval serfs as crawl back under the yoke of Jesuitry? How could the bogs of foggy Ireland and the vegas of sunny Spain nourish equally imperishable roots of a plant that failed to get a firm foot-hold in the sands of Brandenburgh?

The solution of those enigmas can be found in the circumstance that the doctrine of anti-naturalism had extended its influence to the character of many European nations, and that the character-traits of a race are less amenable to rapid changes than its intellectual standards. On the soul-organism of the Latin races the thousand years influence of monastic tyranny has left traces which the light of science will fail to efface for centuries to come. The propaganda of a manlier creed has thus been defeated, not only by their ignorance, but by their aversion to mental efforts, by their habitual reliance on miracles, by their incurable indifference to the claims of truth and the merits of intellectual independence, by their hereditary mistrust in the competence of their natural instinct. To their moral palate a doctrine which nauseates their northern neighbors has become a pleasant narcotic; they have been forced to swallow the opium of pessimism till a craving for the repetition of the mind-enervating dose has become a second nature; they hug the cross that has proved a symbol of death to their noblest reformers.

Against that influence of perverted instincts the logic of mental revelations avails but little. “Propositions which would appear self-evident to certain mental constitutions,” says Dr. Carpenter, “are apt to be very differently received by others, according to their conformity or discordance with that _aggregate of preformed opinion_ which has grown up in the minds of each. For just as we try whether a new piece of furniture which is offered us does or does not fit into a certain recess in our apartment, and accept or decline it accordingly, so we try a new proposition which is offered to our mental acceptance. If it either at once fits in or can by argument or discussion be brought to fit in to some recess in our fabrics of thought, we give our assent to it by admitting it to its appropriate place. But if it neither fits in the first instance nor can by any means be brought to fit, the mind automatically rejects it.”

It is true that logical demonstrations may become complete enough to defy dissent, but even from facts which force themselves upon the acceptance of every rational human being, different individuals will draw widely different inferences. That the mind of man may become a receptacle for irreconcilable doctrines is strikingly illustrated, by the simultaneous acceptance of the Old and New Testament of our heterogeneous scripture, and in the same way obstinate bigots manage to associate scientific truth and dogmatic absurdities. Darwin and Moses may occupy adjoining quarters in the fabric of the same cosmogony; the rule of three may become a passive concomitant of Trinitarian dogmas. The torch of truth may be permitted to flicker in a secluded recess of souls which refuse it the privilege of throwing its rays in certain directions. Education may fail to reclaim hereditary bigotry. In the winter of 1559 the rabble of Madrid assembled to witness the death of Don Carlos de Seso, a Spanish nobleman whose ancestors had fought at Granada and Toledo. His brother had been the favorite hunting-companion of Charles V.; one of his uncles had sacrificed his life in deciding the victory of Pavia; Don Carlos himself had acquired renown both as a soldier and a scholar, but in the latter capacity he had confessed his sympathy with certain doctrines of Martin Luther, and the Holy Inquisition had sentenced him to anticipate his doom in the flames of the stake. King Philip II. honored the _auto da fé_ with his presence, and frowned in a way which the condemned freethinker mistook for a disapproval of his sentence. “O King! can you thus witness the torture of your subjects?” exclaimed De Seso. “Deliver us from so cruel a death which even our enemies admit we have not deserved.” “I would help carrying faggots to burn my own son,” replied the King, “if he had incurred your unspeakable guilt.” Yet Philip the Second was one of the best-educated princes of his century. In mathematics, astronomy, ancient and modern languages, geography, and history, he was far better informed than Landgraf Philip of Hessen, who would have risked his own life to save that of a loyal cavalier.

There are mental mummies who cannot be revived by removing their grave-shrouds and clothing them in modern drapery; the principle of conservatism has penetrated their very veins and the marrow of their bones. It is by no means unconceivable that a popular leader like Garibaldi or Porfirio Diaz should succeed in persuading a million of his countrymen to renounce the yoke of Rome and build Protestant chapels, but the result would be largely limited to a change of nomenclature. Before long the dissenters would march in procession with a wonder-working tooth of John Wesley or kiss a shred from the petticoat of the Holy Maid of Kent. They would groan at the mention of Rome, but exorcise spooks with the initials of Ulric Zwingli, and abstain from work on the anniversary of every Protestant martyr. They would try to redeem drunkards by sprinkling them with consecrated water from the holy rivers of Kansas, and celebrate Arbor Day only by invoking the spirit of Prof. G. P. Marsh, as a patron-saint of climate-improving forests. Under the stimulus of industrial influences, they might transfer the cross from way-side shrines to telegraph-poles, but they would persist in the worship of sorrow.

The creed which has turned the happiest countries of our globe into a grave of their former prosperity, is a medley of miraculism and anti-naturalism, and the experience of the last century has proved that both can survive the repudiation of Rome and even of Galilee. The mania of renunciation, after the abolishment of monasteries and nunneries, continued its dismal rites in Quaker-garb and Shaker temples of celibacy. The miracle-hunger of millions who have learned to scorn the clumsy tricks of the cowled exorcist, gratifies its appetite in the mystic gloom of the dark cabinet. Rustic supernaturalists, deprived of such luxuries, indemnify themselves by retailing the marvels of the serpent-charm and joint-snake superstition.

A curious psychological problem suggests itself in the question how far the charm of the “sour-grape philosophy” may contribute to the persistence of certain forms of moral nihilism. Condemned criminals almost invariably “renounce the vanities” of a life which the Court of Appeals has refused to save, and in a scaffold-speech, quoted in Galignani’s _Messenger_ of May 6th, 1837, the English murderer Joseph Greenacre expressed his conviction that his crime had been the means of saving his soul, because “death on the gibbet was one of the surest passports to heaven.”

For similar reasons degenerate nations, after realising the doom of their national welfare, are apt to renounce the glory of a forfeited world, and to consider misery, poverty, and shame so many stepping-stones to the bliss of a better life beyond the grave. After habitual sins against the health-laws of nature have avenged themselves in cureless diseases, decrepit bigots may find solace even in that most insane tenet of their dualistic creed which teaches them to despise the body as the enemy of the soul.

A natural effect of pessimism may thus, in course of time, become one of its perpetuating causes.

FELIX L. OSWALD.

THE NERVOUS GANGLIA OF INSECTS.

I.

Although the internal structure of the brain of insects has been the object of numerous and important investigations, among which we must place those of Dietl, Flögel, Bellonci, and Viallanes (who have applied the method of sections to the study of this organ), no attention has as yet been paid to the other nerve-centres of insects, and in particular to the ganglia of the ventral chain. Writers have contented themselves with describing the external form of these ganglia, and their anatomical relations to the other organic parts; but nothing has been done to throw light upon their inward structure. All the knowledge which we have on this subject is very meagre and dates far back to the works of the old writers, who, like Newport, had at their disposal no other means of study than the microscopic examination of organs viewed either transparently or in dilacerated preparations. A method so defective could render but incomplete results, and indeed in many cases erroneous ones.

We have sought to supply this much to be regretted lack of entomological knowledge, by applying to the ventral ganglia of insects the admirable method of sectional cutting, which has brought about such marked advances in contemporaneous zoölogy.

I need hardly insist on the interest of this research. We shall only remark that all anatomical study bears an unfinished aspect, up to the moment at which we grasp the meaning of the organs which we describe; physiology is a necessary complement of anatomy, it is that which gives to it a meaning. Therefore, when we dissect an organ, which, as in the case of an insect’s brain, is endowed with the most complex psychical properties of which these animals are capable, we find ourselves in the presence of parts whose functions almost entirely escape us. What is, for example, that peculiar organ to which we have given the name of the “pedunculate” body? Anatomists have described with the greatest care its connections and portrayed its external contour; but we cannot discover, or even conjecture its uses. It would be necessary to understand the habits of thought and the feelings of an insect, to be able to assign a rôle to parts so complex and so delicate as those contained within its brain.

The study of the ventral ganglia seems to us to be capable of conducting us to a better result, for in everything that concerns these nerve-masses, physiology is more advanced, and, in all cases, clearer. The ganglia of the thorax, for example, are in the main motory centres; the principal nerves that are sent out from them are to be found in the wings and in the feet; the study of the terrestrial, aquatic, and aerial locomotion of insects has already formed the subject of quite a number of important scientific works; we are now upon well-known ground, and we may hope that it will be possible to establish some connection between the anatomical structure of ventral ganglia and the functions which these ganglia control.

This hope appears to us to be the more legitimate, because we can make use of all the resources of comparative anatomy to work out the problem. If we consider any particular function, for example, that of flying, we notice that in species which resemble each other this function is exercised under totally different conditions; the same organ acquires different uses, and these variations become singularly instructive when we can trace their relationship to the particular structure of a nerve-ganglion. Thus, one of the large wings of the dragon-fly, which is almost like a bird in the range and power of its flight, becomes the elytrum of the beetle; the elytrum is a stiff wing covered by chitinised matter and serving as a protection to a part of the thorax and abdomen. Sometimes the elytrum is used in flying, as in the case of the cockchafer. In other lamellicorn insects, in the _Cetonia_ for instance, the elytrum is not used in flight; it merely moves aside so as to allow the second pair of wings to unfold. Its rôle becomes still less active in the golden carabus, in _Procrustes_, in _Blaps_, and many other _Coleoptera_, whose two elytra are found on one vertical line, and form but one single and immovable portion; then the second pair of wings disappear; from the physiological point of view, the animal becomes apterous. In another and different order, the order _Diptera_, it is the second pair of wings that undergo an important modification; they cease to be used in flying, and are transformed into an organ of equipoise: they are used for maintaining equilibrium.

All these physiological variations, taking place in the self-same organ, must in all probability have their counterpart in the internal anatomy of the ganglion that governs the organ, and the comparative study of this ganglion in different species will enable us perhaps to discover the functions of some of its parts. Thus, if we consider by hypothesis, as the nerve-centre of flight, some small lobe which is found occupying this or that place in a thoracic ganglion, the disappearance or modification of this lobe in species not possessing the faculty of flying, might serve to throw additional light upon such an interpretation.

What we have just said with regard to flight is equally applicable to terrestrial locomotion, which also represents in itself many varieties. The typal insect possesses three pairs of feet, whence the name of hexapods, but there are particular species which drop a pair of feet, for instance, the _Lepidoptera_ of the genus _Vanessa_; in others, the physiological function of the foot varies; in the case of the carrion-beetle (a necrophagus coleopter) it serves as an instrument of tillage, to dig with; for the cricket, the third pair of feet are used for the purpose of leaping; for the _Dytiscus_, it serves as an oar, and so on. We must also bear in mind the curious fact that there exists in the larvæ of certain insects what are called supplementary feet, having only a transient existence and disappearing at maturity; the caterpillar, the larva of the butterfly, has five pairs of supplementary feet. These notable facts demonstrated by comparative anatomy, cannot fail to furnish us with valuable information concerning the functions of the complex organs found in the ganglia of the thorax.

But this is not all. We have not enumerated all the contributions of comparative anatomy to the problem which we are now about to consider; we may make use of the method of comparison without bringing the different types into juxtaposition, but by viewing the nervous system of only a single animal in its entirety. We know in fact that the body of an insect is formed by a definite number of segments, all constructed on the same fundamental plan and arranged in a linear series. Each one of these segments is joined to a nerve-ganglion, which is all its own and supplies it with sensibility and motility, the two elementary properties of nervous activity. In the course of development, these ganglia have the power of changing their positions; and it is not uncommon to find that the greater number of the abdominal ganglia move up into the thorax; each one, nevertheless, retaining its nerve-relationship to its own segment. Now all the segments of an insect’s body are not called upon to play the same rôle; a division of labor has been effected among them with regard to the functions which they are found to exercise: as we have already seen, the ganglia of the thorax are essentially centres of locomotion; in the head, one of the ganglia, the sub-œsophageal, furnishes the nerves of the buccal portions; the other one, the brain, is connected with particular nerves and becomes the centre of the highest form of psychical activity of which the creature is capable. We have here a number of modifications superadded to the original plan. Yet the original plan should again be met with in the ganglia that have been least differentiated, such as those in the abdominal region; and the comparison between an abdominal and a thoracic ganglion, for instance, is well calculated to show what are the primal and fundamental structures, and what are the secondary ones which have been superadded and have become necessary for the execution of the more complex functions. The study of embryonic and larval forms so easily observed in insects, will most probably conduct us to the same result. And thus perhaps by continuous efforts, all guided by the same governing idea, we shall ultimately arrive at the analogies that exist between the cerebroid ganglia and the humblest ganglia belonging to the ventral chain, and thus finally be able to understand the action of the nerve-substance.

The importance of this object, which, be it clearly understood, can never be attained except by the united effort of many workers, is well calculated to command our strenuous exertions and to encourage us in surmounting the difficulties of a study which is as yet almost entirely new.

II.

We shall restrict ourselves in this article to the consideration of one particular case; we shall describe a single ganglion of the insect. The type we have chosen, for reasons too lengthy to enumerate, is a Coleopter of the family of _Melolonthidæ_; the _Rhizotrogus solstitialis_, a small beetle very commonly found in the southwest of France. We will now proceed to the consideration of the first thoracic ganglion.

The prothoracic ganglion in the rhizotrogus is joined by very short connective filaments to the second thoracic ganglion, and also to the sub-œsophageal ganglion; this latter ganglion, we must note _en passant_, being situated in the thorax. If with a pair of scissors we sever the head of the rhizotrogus, we find that the remainder of the body contains not only the thoracic ganglia, but also the sub-œsophageal; a peculiarity which, from a physiological point of view, is very interesting.

The ganglion of the pro-thorax, which is greater in width than it is in length, bears a vague resemblance to a cone the base of which is turned towards the sub-œsophageal ganglion, whilst the apex points towards the second ganglion of the thorax. From the lower part spring two large nerves, their starting-point being nearer the ventral than the dorsal surface, a fact clearly comprehended when we find that the fibres of these nerves extend for the most part into the first pair of feet, that is to say, into those organs that lie underneath the horizontal plane of the ganglion. The connective filaments which penetrate the ganglion anteriorly enter it nearer the dorsal surface than the ventral, this last being extremely convex. Dissection throws no additional light upon the anatomy of the ganglion. But by means of a series of sections, we find that it is composed of a mass of fibrillar substance which occupies its centre portion and of a layer of nerve-cells surrounding the fibrillar substance. This fibrillar mass is, owing to its great volume, far the most important, and constitutes in itself alone about four-fifths of the organ. The fibrillary structure can only be satisfactorily analysed by using on it osmic acid, or other equivalent reagents which dissociate it and admit of its being reduced to a certain number of clearly differentiated elements. Whenever osmic acid or a similar reagent has not been employed, or has not sufficiently penetrated the ganglion, owing to the obstacle presented by a thick conjunctival covering or envelope, the fibrillar substance takes on a homogeneous aspect that effectually renders all analysis of it impossible. Everything depends on the employment of a good method of preparation.

When the ganglion has been properly prepared, we perceive a very material difference in the appearance of the fibrillar substance when we compare the dorsal with the ventral region of the ganglion. We can do this very satisfactorily by a longitudinal section, extending through both regions. In such a section close to the median line but not confounded with it (see Cut 16)[9] we perceive that the ventral region is occupied by a cord or string of substance which owing to the action of the osmic acid has become very black, and which is formed of so dense a tissue, that we can with difficulty separate it into fibres and fibrillæ. This cord, which, by reason of its position and shape, I propose naming the _ventral column_, extends over the ventral surface of the ganglion in a longitudinal direction; at both its anterior and posterior extremities it is carried on by fibres extending into the ventral columns of the other ganglia, in such a manner that the entire series of ganglia are united by one continuous ventral cord.

If we look at a transverse section (see Cut 26), the cord, which is recognised by its dark color and by its position near the ventral surface of the fibrillar substance, will be seen to have the form of two almost perfect circles. The ventral column thus presents a circular section, is duplex and symmetrical: there exist two separate and distinct ventral columns, separate at least for a certain length; a fact which must be considered in connection with the primitive duality of the ganglion.

In every section where the columns remain distinct from each other, they are separated either by fibres and conjunctival cells, or by nerve-fibres emanating from the cells of the ventral region and proceeding in an upward direction between the two columns. At the other points, the two columns join on the median line. This union is effected in different ways, either by the two columns coming directly together, thus merging into a single mass, or by a commissure which describes the arc of a circle underneath the two columns, or else by the inferior ventral lobule.

We give the name of inferior ventral lobule to a small lobule of fibrillar substance, situated beneath the ventral column. When looked at in a horizontal section not passing through the median line (see Cut 17), this lobule presents the appearance of a rounded protuberance, breaking the almost rectilinear contour of the ventral column. As this characteristic peculiarity is repeated in the internal structure of all the ganglia, we may use it to ascertain the number of the ganglia, whenever these present the appearance of being fused into one compact mass; we may see the practical application of this remark by observing the sub-œsophageal ganglion.

In a succession of horizontal sections, the starting point of which is the ventral region, the first mass of fibrillar substance met with by the knife is the inferior ventral lobule, which is formed (see Cut 1) by two rounded fasciculi, placed symmetrically on either side of the median line and joined together by a transverse commissure.

In these sections, we also perceive fibres of the crural nerve, which, after having extended over a certain length of the ganglion, penetrate into the substance of the inferior ventral lobule (Cut 2). In transverse sections (Cut 23) we find the two ventral lobules placed beneath the two columns which they help to support, and into which they gradually merge; and we also perceive the transverse commissure which joins the two. We shall call this the _transverse commissure of the inferior ventral lobule_.

Let us now pass on to the examination of the upper surface of the ventral column. This surface is covered by a cluster of very fine fibrils rather sparsely disposed; we can clearly follow their course by means of a longitudinal section (Cut 17); we see them again in a horizontal section (Cut 5). To continue the general description of the ganglion we must now consider the dorsal region. It is, as we have previously stated, occupied by a fibrillar substance not so dense as that which composes the ventral column, and we will give the general name of dorsal lobe to this region, reserving the name ventral lobe for the region which embraces the ventral column and its adjoining parts. The dorsal lobe presents as its distinctive characteristic the feature that it is crossed longitudinally by a succession of connective filaments clearly seen in the longitudinal section of Cut 16.

We have already stated that the ventral column receives fibres issuing from the ganglion in front and sends out others to the ganglia in the rear. We shall call the totality of these fibres _the connective ventral filaments_, and shall call the totality of those that traverse the dorsal lobe _the dorsal connective filaments_.

The connective filaments which join the sub-œsophageal to the first thoracic ganglion, and which, between these two ganglia, are composed of a dense fasciculus of fibres, distribute these fibres, at the point at which they enter the prothoracic ganglia, in different directions; one set of fibres proceeds towards the ventral column, these are the ventral connective filaments; a second set traverses the dorsal lobe, and are the dorsal connective filaments.

Whilst the ventral connective filaments soon merge into the very dense substance of the ventral column, the dorsal connective filaments, on the contrary, remain distinct from the organs which they traverse, and preserve their individuality throughout. They take directions in three different planes (see Cut 16), consequently they can be subdivided into superior, medial, and inferior dorsal connective filaments.

Newport seems to have observed this distinction of fibres; and he has given the name of sensory column to this first division, and that of motor column to the second. Unfortunately the drawings and figures he has published, though schematically correct, are not clear. We do not adopt his terminology, in the first place because he designates the organs after their supposed functions, and we have made it a rule never to use controvertible physiological suppositions to designate anatomical organs; and besides, though the name of column is applicable to the connective ventral filaments, we cannot apply it to the connective dorsal filaments, which are subdivided into three pairs of fibrous fasciculi and do not in the least resemble a column.

In the study of _Melolontha vulgaris_, we have been able to establish in the most absolute manner that there exists a considerable histological difference between the connective filaments of the ventral region and those of the dorsal. Though we have not yet noticed this difference in _Rhizotrogus_ in any marked degree, nevertheless it has seemed to us needful to point it out here, because the fact is of such vast importance that it cannot fail to be general. The dorsal connective filaments, whilst they preserve their individuality in their passage across the dorsal lobe of the ganglion, penetrate nevertheless into some small masses of dotted substance which are found in the path of their entrance into the ganglion. The mass annexed to the inferior dorsal connective filament, is above all very important and is directly connected with the ventral column. As the connective filaments are in pairs, each of these possesses a distinct mass of fibrillar substance and both the masses attached to the same pair of connective filaments are joined by a commissure.

Let us now say a few words about the nerves which proceed toward the prothoracic ganglion. There exists here but one single pair of nerves, extremely important and very extensive. This is the crural nerve. To this nerve are attached the organs which are superadded to the primary structure of the ganglion, such as we have described it, and which in consequence renders the primitive structure more complex. We shall perceive the importance attached to the idea of a _superadded_ organ, when we study the abdominal ganglia, where the organs we are about to describe are either completely wanting or are but imperfectly developed.

If now we examine a transversal section taken a little in front of the place from whence the crural nerves emerge (Cut 19), we shall notice that the central part of the ganglion is occupied by the ventral column and the upper part by the dorsal lobe. In addition to this, in the lateral regions of the ganglion we find two important masses of fibrillar substance. At this point these two masses remain distinct from the parts we have just mentioned, and on the other hand they are in connection with the crural nerves. The latter send a part, and unquestionably the greater part, of their fibres into the lateral lobes. In a section slightly posterior to the preceding one, also transversal, a very important change has taken place; the two lateral lobules, always connected with the crural nerves, have also established connections with the centre of the ganglion, and in the sections further on the fusion is complete. As these lateral lobules possess the characteristics mentioned, only at the point at which the crural nerves emerge, we shall call them the _crural lobes_. Thus we find in the prothoracic ganglion three principal lobes: (1) the crural lobe, which is double, symmetrical, and lateral, (2) the dorsal lobe, (3) the ventral lobe. These two last, in contradistinction to the crural lobe, will be classed together under the common term _central lobe_.

And now to finish this summary description of the prothoracic ganglion, we will point out an important disposition of the connective tissue which divides the ganglion into two halves, one anterior, the other posterior. We can easily understand this disposition by looking at a longitudinal section passing exactly through the median line. From the dorsal surface of the ganglion, may be seen descending a bundle of cells and connective fibres, which, in the form of a column, are directed toward the centre of the ganglion; these cells and fibres do not meet any important organ on their way, the dorsal connective filaments always taking a lateral course. A fasciculus, similarly composed of cells and conjunctival fibres, starting from the ventral surface of the ganglion, appears to meet this conjunctival column (Cut 18). This curious disposition appears to be, as M. Henneguy has ingeniously suggested to me, a trace of the anterior development of the ganglion which had been formed of two distinct portions that have been naturally _welded_ together along the median line; the connective fasciculi corresponding to the point where the welding has been incomplete, and representing the survival of a portion of the walls of the two ganglia.

III.

As the ganglion which we have just described contains some structural difficulties not easy of comprehension, let us proceed with our description under another form, following the order of our illustrations.

Figure 1 is the first horizontal section, cut through the ventral region of the ganglion; the knife has here met the lower ventral lobule, which at this point shows itself double; the two halves being joined by a double transversal commissure. Section 2, made at a point a little higher than the preceding one, shows us at the centre the lower ventral lobule as increased in size; and in the lateral part of the figure appears a new organ, the crural lobule, which is here entirely merged into the lower ventral lobule. The crural lobule is traversed by fibres from the crural nerve, which instead of being entirely lost in its substance, proceed still further, passing into the lower ventral lobule. Section 3 merely brings into prominence an important transversal commissure. In Section 4, the inferior ventral lobule is replaced by the ventral column, which appears double, is symmetrical, and united by a transversal commissure; this commissure being formed of fibrillar substance. The ventral column is closely connected on each side with the crural lobule; it is besides crossed by the ventral connective fibres, which can be seen emerging from its anterior and posterior extremities. Section 5 allows us to examine thoroughly the disposition of those ventral connective fibres; we see that while they penetrate the ganglion, they also pass through two symmetrical masses of fibrillar substance; these two masses, which we name the anterior ventral lobules, are joined together by a transversal commissure. After having traversed the anterior ventral lobules, to which it appears they give a portion of their fibres, the ventral connective filaments pass through the ganglion in an antero-posterior direction, and we see them penetrating the two posterior ventral lobules. The last named lobules, which remind us by their position and appearance of the anterior lobules, receive in addition fibres issuing from the crural lobules; but they do not receive them all, because we notice quite a number of these fibres advancing directly into the second thoracic ganglion. After emerging from the posterior ventral lobules, the ventral connective filaments pass into the second thoracic ganglion, where we see them penetrate into the anterior ventral lobules.

With Figure 6, we leave the ventral lobe of the ganglion and come to the lower portions of the dorsal lobule. The important filaments crossing this section from the front to the back are called lower dorsal connective filaments. We notice as they proceed some small masses of dotted substance, and, in addition to these, dark colored dots which are the result of the knife having cut crosswise through several fascicles of ascending fibres. We shall find out by means of the sections taken from different parts and placed so as to allow of our better observation, what these ascending fibres are. The crural lobule, always exhibits the same characteristics. We have given it a homogeneous aspect in our drawing. As a fact it presents in its sections a vast number of structural details. But these details being very difficult to understand, we prefer not to dwell upon them.