CYTOMORPHOSIS 



31 



The developing nerve fibrils I have already mentioned. In 

 nerve cells there appear very fine fibers which develop grad- 

 ually, making a network in the cell, Fig. 19. There also appear 

 deposits of a substance which reacts to stains differently from 

 the protoplasm and the fibrils, Fig. 18, k, k' . The deposits in 

 question have received the somewhat fantastic name of "tig- 



FiG. 18. — Motor nerve cells from the spinal cord of a rabbit, ke, nucleus; den, 

 dendrite; Ax, nerve fiber, and x, its origin; k, k', Nissl bodies. — After K. C. Schneider. 



roid substance." We notice also peculiar cavities which form 

 a net-work in the protoplasm of the cell, and are filled with 

 fluid. In the gland ceUs one sees the material distributed in 

 the protoplasm which is utilized later for the execution of the 

 specific activities of the gland cells. Fig. 20 This material is 

 not the secretion proper, but a primary stage. In quite 

 another wise do the intervening supporting tissues develop, 

 for in them the cells show a strong tendency to separate from 

 one another and to produce special structures in the inter- 



