tissue (tis'su)

A collection of cells or structural elements so modified in form, size, and arrangement as to have a constant and recognizable structure, wherever it may occur (being modified in different situations only so far as local connections and vises render nece ary), and to be adapted to the performance of a special and definite function. All of one kind of t. in the body forms a system, such as the nervous or the muscular systern, while the. t's combined form organs. Two systems of cla ification are used, the older and more common being based upon the appearance in the adult, and the other upon the origin from the different germ layers of the ovum. According to the first method, one of the most satisfactory cla ifications is the division into four groups — epithelium, connective t., muscular t.,