GENERAL CONFORMATION AND HISTOLOGY OF BRAIN. 



41 



The nerve-fibres arise from the ganglion-cells. R. Wagner 

 first showed that but a single process of these cells could he 

 traced directly into the nerve, and other investigators have con- 

 firmed this. The relations which the other processes of a multi- 

 polar cell and the processes of the cells which do not possess this 

 'axis-cylinder" process have to the nerve-fibres remained in 

 darkness until Gerlach, in 1870, showed that these processes 

 form a net-work with each other, and that from this net-work 

 nerves arise. It is only 

 during the course of the 

 past year that Bellonci first, 



and later, in a still more / fa JERPWJS1 

 manner, 



convincing 



Golgi 



and Bela Haller succeeded 

 in showing the method of 

 origin of nerve-fibres from 

 the central ganglioiiic cells. 



O O 



Golgi conducted his investi- 

 gations on the cortex of 

 human beings and of other 

 animals, and, by frequent 

 combinations of very com- 

 plicated microscopical pic- 

 tures, arrived at the same 

 conclusions with Haller, 

 who worked on mollusks, 

 where the conditions were 

 more simple, and the relations could be plainly seen. The most 

 important of these discoveries, which, moreover, have been con- 

 firmed for other parts of the central nervous system by Golgi's 

 pupils, is the now well-established fact that the nerve-fibres arise 

 from the cells of the central nervous system in two ways; that 

 there is a direct and an indirect origin of nerves. 



The former we have already mentioned as having been dis- 

 covered by Wagner. The axis-cylinder process of a ganglion-cell 



FIG. 24. 



From a section through the pleuro-cerebral 

 ganglion of the flssurella. 1, net-work of nerves; 

 2, ganglion-cells ; 3, nerve-fibres. (After Heiile.) 



