GANGLION-CELL AND NEBVE. 31 



But it soon became apparent that this valxiable discovery had only 

 opened the way to other much more significant ones: that it held only a 

 part of the truth. A Spanish scholar, Eamon y Cajal, who worked with the 

 Golgi silver method, published in close siiccession a series of studies whose 

 results — confirmed and amplified by KoUiker, G-ehuchten, Waldeyer, Len- 

 hossek, and others — lead us to new views. We stand yet in the current of 

 changing opinions, receiving daily new contributions to this interesting 

 question. We can already picture to ourselves the minuter relations of the 

 elements in the central nervous system. But this picture which is to be 

 developed is not founded upon purely anatomical investigation. At the 

 same time that histological preparations brought us to the new views. His, 

 on the basis furnished by embryology; Forel and Monakow, from studies 

 in the realm of pathology, came to a conception of the origin and end of 

 nerve-tracts which nearly coincides with that reached by the anatomical 

 method. Eetzius finally succeeded, indeed, in demonstrating, through vital 

 methyl-blue reactions on the living nerve-cells of many lower orders of 

 animals, much which harmonizes well with conclusions from histological 

 preparations. 



The ganglion-cells usually send out two kinds of processes from their 

 bodies: a moderately-fine process, the neuraxon, neurite, or axis-cylinder, 

 which is first to spring from the cell; and the thicker dendrites or proto- 

 plasmic processes, which break up into fine twigs. The dendrites appear 

 somewhat late in embryonic development. The neuraxons always end ap- 

 parently by breaking up into branches. Two kinds of cells can be differ- 

 entiated: (1) those in which the process is so short that the ramifications 

 lie close by the cell (Fig. 153, g) and (3) those with long-extended neuraxons 

 (Fig. 153, d and /). Along its course, which sometimes extends for many 

 centimeters, such a process gives ofi; more or less numerous lateral branches, 

 or collaterals. These also end, like the main process, in fine subdivisions. 

 We have long known that the neuraxon of a nerve-fiber is composed of 

 numerous separate fibrillse. So there is nothing striking in the statement 

 that along the course of the nerve individual fibrillse branch off from the 

 main trunk. Naturally, one has very infrequent opportunity to follow a 

 neuraxon with certainty from its origin to its end. But all that has been 

 learned regarding the termination of this important cell-process, — what has 

 been observed, and what has been inferred from prepared specimens, — in- 

 dicates that it, in triith, branches out into fibrillse at its termination. If 

 it passes out from the central system to the periphery, as in the spinal nerve- 

 roots, it ramifies in the muscle-tissue — motor end-plates — or between epi- 

 thelial cells — plexuses of the sense-organs. But relatively few of the neu- 

 raxons pass to the peripheral organs. Very much the greater part of them, 

 after a shorter or longer course, come into relation with another cell, grasp- 



