4 Journal of Comparative Neurology. 



searches of v. Miiller and the illustrious works of v. Monakow 

 show that the cells of the corpus geniculatum externum are not 

 a nucleus of the optic nerve, not a " Zellencomplex " in the 

 sense of His. 



The presence of the striated musculature when there is 

 total absence of motor roots is unquestionably a fact of great 

 importance and shows us that the cells of the ventral cornu of 

 the spinalcord do not play any role as trophic centres for mus- 

 cles. In other words, the development of the striated muscles, 

 which are formed from mesoderm, does not depend, up to a 

 certain given moment, upon the cells of the ventral cornu 

 and the development of the muscular system is possible even in 

 the absence of the spinal cord, motor cells and roots ; the pres- 

 ence of the sensory ganglia and nerve-fibres suffices for this de- 

 velopment. At first sight the pathologico-physiological data of 

 the adult organism seem to contradict this, in view of the fact 

 that alteration of the cells of the ventral cornu of the adult cord 

 invariably produces a pronounced muscular atrophy. This con- 

 tradiction is easily explained by the difference between the 

 functional role of the ventral cell of the adult spinal cord and 

 that of the embryonic cell. Moreover, in the adult cord, aside 

 from the purely anatomical connection there is a functional con- 

 nection. The functions of the muscular fibres — protoplasmic 

 contraction, voluntary movement — are the result of impulses 

 carried from the cell toward the muscle. The vital function of 

 the muscles, that is to say, movement, depends upon the ven- 

 tral cells of the cord, which are also responsible for the nutrition 

 of the muscles of the adult organism. These facts elucidate the 

 general law of trophic nerves: a functional connection between two 

 organs implies also the idea of a trophic connection. 



The author's conclusion, as here expressed, is of great im- 

 portance and if properly understood and applied would render 

 unnecessary much of the recent theorizing upon the subject of 

 trophic nerves and trophism in general. It cannot be too 

 strongly urged that every physiological connection in the body 

 is a mutual relation. No organ can exert an influence upon an- 

 other organ without being itself modified thereby to a greater or 



