20 ANATOMY OF THE CENTEAL NEKYOUS SYSTEM. 



suffices to innervate the large electric organ. Quite different appearances are 

 obtained according to the technique used in the preparation of the ganglion- 

 cells. In Fig. 4 two ganglion-cells are represented as they appear after 

 treatment with carmin and picrocarmin. Fig. 6 (D) shows a cell treated 

 according to the Golgi method in which the silver precipitate shows the 

 processes in a beautiful way before unequaled. Of the structure of the cell 

 nothing can be seen. Structural figures, important in investigations in the 

 realm of pathology, are only gotten in other ways. Fig. 6 (A and B) shows 

 what microscopic technique has accomplished up to the present time. 

 Many ganglion-cells bear pigment of yellowish-brown color. In the two 

 cells figured the pigment is indicated in dotted black. 



The nerve-fibers originate from the ganglion-cells. Wagner first 

 showed that in many of these cells only one process may be followed directly 

 into a nerve, and other investigators have confirmed it. This process is 

 called a Neuraxon, an Axis-cylinder Process, or a Neurite. What became of 

 those neuraxons which did not pass into nerve-trunks; what role was played 

 by the other processes of the cell, — the protoplasmic processes, or Den- 

 drites, — remained in complete obscurity until Gerlach stated in 1870 that 

 all these form among themselves a net, and from this there arise nerve- 

 fibers again. 



In the course of the last few years our knowledge has undergone an 

 unexpectedly extensive amplification, made possible by the progress of his- 

 tological and of histo-physiological technique. First Bellonci, through 

 osmium staining, then still more conclusively Golgi, through treatment of 

 the cells with sublimate or even with silver precipitates, succeeded in demon- 

 strating that from some cells the neuraxon passes directly into a nerve-fiber, 

 but from other cells neuraxons arise which break up into a net-work. 

 Lateral twigs coming from those neuraxons which arise from the first- 

 described cells are said to take part also in the formation of this net-work. 

 Golgi supposed that nerve-fibers pass out again from the net-work. There 

 is then a twofold origin for nerve-fibers: one direct, the other indirect, 

 through the means of the net-work. The dendritic processes, it is asserted, 

 have nothing to do with the formation of nerve-fibers. Such were the 

 results of Golgi's observations. 



What Golgi inferred from the study of numerous, sometimes compli- 

 cated, views of the brain-cortex and spinal cord of man and mammals, 

 Haller was able to see directly in the ganglia of mollusks and worms, where 

 the histological relations are very distinct. But, according to his view, the 

 net-work arises from cell-processes which are essentially equivalent one to 

 another. Through these studies, as well as those of Nansen and others, 

 the proof seemed conclusive that there are two modes of origin of nerve- 

 fibers: a direct one and one through the medium of a net- work. 



