120 Journal of Comparative Neurology. 



ation presents itself. In this case the axis-cylinders of the 

 central stump grow out again towards the muscles to which they 

 belong, if, at least, they can follow a bed along which to grow, 

 especially after nerve-suture. The study of Forel contains a 

 number of considerations on the slight differences between what 

 is seen in the animal when operated young or old, and also be- 

 tween various findings in man, and, further, illustrations of the 

 problems in the anatomy of the fillet ( retrograde atrophy and 

 retrograde degeneration), of the auditory centers, trigeminus 

 and pyramidal tract. 



The problem of experimental anatomy of the brain might be 

 formulated as we have it now on ground of this early study of 

 Forel. He did not summarize it in the following words but has 

 all the material expressed in the various parts of the paper : 



1. All nerve-fibers are merely processes of cells. They 

 terminate blindly in end-brushes, like the protoplasmic pro- 

 cesses without anastomoses. The interrelation of the nerve- 

 elements takes place by contact, not by the continuity of a net- 

 ivork. The net-work of Gerlach is a false net-work [comparable 

 not with a net, but with the appearance of a dense forest where 

 each twig belongs to only one tree, although it may be difficult 

 on a photograph to trace each correctly]. 



2. To call the cell body the trophic center of a nerve-fiber 

 is justified only in the sense that the nerve-fiber is a part of the 

 entire cell and that it is subject to the general laws of cell-vitali- 

 ty. (Any part of the cell which is cut off from the nucleus will 

 degenerate). 



3. The results of experimental anatomy and the so-called 

 secondary and tertiary degenerations are satisfactorily explained 

 on this basis ; further, a discussion of secondary degenerations 

 etc. is only complete when the questions are put with these 

 facts in view. We should not merely study fiber-tracts but 

 always search for the cell-bodies to which the fibers belong. 



Forel does not summarize all the conclusions, since his aim 

 is rather the explanation of certain disputed facts relating to von 

 Gudden's atrophy method. In a later publication he furnishes 



