86 THE CELL DOCTRINE. 



minal matter and the masses immediately adjacent, 

 of which the .cartilage or tendon is composed ; and 

 such a line would correspond to the outer part of 

 the surface of an epithelial cell.* In very young car- 

 tilages, as in very young epithelium, the cells consist 

 of germinal matter only, with a small quantity of 

 soft formed material intervening; and to understand 

 the true relation of the cells to the intercellular sub- 

 stance, the tissue should be studied at different pe- 

 riods of its growth. 



So, too, a " cell " or elementary part of muscle or 

 nerve, would consist of a mass of germinal matter 

 (the so-called nucleus), with a portion of muscular 

 or nervous tissue corresponding with it, and with 

 which it is uninterruptedly continuous. 



In the formation of the contractile tissue of muscle, 

 the germinal matter seems to move onward, under- 

 going conversion at its posterior part, into the mus- 

 cular tissue, white it maintains itself by absorbing 

 and converting pabulum. This will be understood 

 by reference to Fig. 13. The fibres of yellow elastic 

 tissue are formed in precisely the same manner. (See 

 Plate, Fig. 14.) Nerve fibres, which in their com- 

 pleted state consist almost wholly of formed material, 

 are similarly produced. In the young state, the fibre 

 is composed of masses of germinal matter, linearly 

 arranged, and in close proximity. As the conversion 

 takes place and the fibre is produced, these become 

 more widely separated, and the tissue resulting from 

 such conversion is nerve. (Plate, Fig. 15.) 



* Beale, Protoplasm, pp. 51-2. 



