196 



NEIIVE-CENTKES 



[CII. XVII. 



In preparations made by Golgi's chromate of silver method, the 

 cells and their processes are stained an intense black by a deposit of 



silver. The various structures 

 in the cells (nucleus, granules, 

 fibrils, etc.), are not visible in 

 such preparations, but the great 

 advantage of the method is that 

 it enables one to follow the 

 branches to their finest ramifica- 

 tions. It is thus found that the 

 axis cylinder process is not un- 

 branched, as represented in fig. 

 208, but invariably gives off 

 side-branches, which are called 

 collaterals ; these pass into the 

 adjacent nerve-tissue. The axis 

 cylinder then acquires the 

 sheaths, and thus is converted 



FIG. 209. Pyramidal cell of human cerebral cortex. 

 Golgi's method. 



into a nerve-fibre. This nerve-fibre 



sometimes, as in the nerve-centres 



after a more or less extended 



course, breaks up into a terminal 



arborescence enveloping other 



nerve-cells; thej. collaterals also 



terminate in a similar way. The 



longest type I of axis cylinder is 



that which passes away from the nerve-centre, and gets bound up 



with other similarly sheathed axis cylinders to form a nerve; but 



H 



FIG. 210. Cerebral cortex of mammal, prepared 

 by Golgi's method. A, B, c, D, F, nerve-cells ; 

 E, neuroglia-cell. (Ramon y Cajal.) 



