262 Journal of Comparative Neurology. 



the guide as to the ability to recuperate. When the nucleus be- 

 gins to be homogeneous, deeply stained, round or oval, but 

 smaller, finally losing the capsule, so that it lies in an area of 

 light plasma, Nissl speaks of the grave alteration indicating the 

 fatal disorganization (Z. f. Psych. Vol. 54, p. 47.). There are 

 a number of facts which force me to leave this point undecided 

 and not to join Nissl in his verdict, but this does not belong 

 here, being of no fundamental importance for the neurone-the- 

 ory. It is a detail-question, how far the nucleus must be altered 

 to lose the power of recuperation. 



It will hardly be necessary here to rehearse the processes 

 of degeneration and regeneration of the peripheral motor nerve- 

 fiber. Only the following data seem to be worth special atten- 

 tion : 



1. The most vulnerable part of the fiber is the final ter- 

 mination in the end-plate (Gessler), then the axone and next 

 the medullary sheath. The latter being most accessible to 

 rough methods shows the alterations readily. 



2. Notwithstanding constant revival of the 'growth of 

 axones in the nerve-end which was cut off, ' we can trust compe- 

 tent investigators who say that the regeneration of the axone 

 always proceeds from the cell or at least from the stump which 

 remains in connection with the cell. 



3. The 'trophic function of the anterior horn cells' is 

 no special trophic function for the fiber but a necessary side of 

 the cell-theory. It is evident that a process of a cell depends 

 on the integrity of the nucleus and cell-body. The relation of 

 the muscles-fibers and the neurones governing them is however 

 a trophic relation between the entire neurones and the muscle- 

 fibers. Whether the neurones be affected in the cell-body or 

 in the fiber or termination, does not influence the mode of al- 

 teration of the muscle. The latter depends on the activity and 

 condition of the motor neurones as a whole. 



For the appreciation of the life and activity of a segmental 

 afferent neurone, I add the results of an interesting study of 



