Chapter XIX: Section 57: It is convenient to divide tissues into three classes,

though the divisions are by no means clearly marked, nor have they any scientific value. The first of these comprises tissues composed wholly, or with the exception of an almost imperceptible cementing substance, of cells; the second division includes the skeletal tissues, the tissue of mesentery, and the connective and basement tissue of most of the organs, tissues which, generally speaking, consist of a matrix or embedding substance, formed by the cells and outside of them, as well as the cells themselves; and, thirdly, muscular and nervous tissue. We shall study the former two in this chapter, and defer the third division until later.