A text-book of anatomy / edited by Frederic Henry Gerrish.

Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of anatomy / edited by Frederic Henry Gerrish. Source: Wellcome Collection.

    41/926 (page 37)
    ELEMENTARY TISSUES, AND THE STRUCTURE OF MEMBRANES AND GLANDS. By F. H. GERRISH. AFULL pi-esentation of microscopic anatomy would require a large volume. It is the main purpose of this chapter merely to give a brief description of the elementary tissues which enter into the formation of the body. Without a knoAvledge of these primary textures much that must be said of the gross anatomy of different parts will be unintelligible ; indeed, it is impossible to understand any organ, either from the anatomical or physiological point of view, unless the mate- rials of which it is composed and the various physical properties of these sub- stances are known with perfect familiarity; for the tissues are to the organs as the letters of the alphabet are to written words. The minute structure of the viscera will be described in connection with the macroscopic features of each organ in turn. CELLS. The word tissue means, in ordinary parlance, a web-like structure or a woven fabric. Anatomically, it is applied to any organized substance in the body. Notice that in this definition the word organized is used, not organic. The latter would, indeed, exclude the substances which are inorganic—that is, all of the ultimate elements, of which there are many in the body—leaving them to the consideration of the chemist; but it would include quite a number of sub- stances found in the body which, although organic, have no title to be called structures, and belong in the domain of the physiologist, who deals with the proximate jirinciples. Thus, albumin and fibrin are organic substances, but not organized; and, consequently, they are not tissues, for tissues are always organ- ized. Every tissue originally consists of microscopic particles, named cells, which have been aptly called the simplest expression of tissue. Etymologically, the word '■' cell is an unfortunate designation, based upon a mistaken belief as to the structure of the corpuscle. At first it was thought that cells were cysts, sacs, vesicles, with fluid contents. But it was long ago learned that they are usually solid bodies, and hence a word which implies the existence of a cavity, as does cell (Latin, cella, a small, hollow cavity), is a misnomer in the majority of cases. However, the substitutes proposed have not met with general favor, and cell has become so firmly fixed in our nomenclature that we shall not attempt to displace it; indeed, there is no call to do so, since no confusion need arise from its use in this arbitrary sense. Not only is it true that all of the tissues primarily are composed of cells, but, going back much farther than this, we recognize the origin of the entire body from a single cell, the ovum (egg). This enforces the saying, which has become almost an axiom, that every cell comes from a pre-existing cell.