(24) 



not at all, or only for a part (as collateral) from the same cell elements 

 as these, while with regard to the part of the psalterium situated 

 under the callosum, it must be assumed that all the tibres are 

 collaterals of the ammonal projection neurites M. 



In a physiological respect, what has been found supplies an 

 anatomical substratum for the closely connected, simultaneous working 

 of both hemispheres in all functions, the inciting stimulus of which 

 has its last and "most peripheral" cortical origin in the sub-granular 

 layers of the cortex. On the other hand, the ending of many tibre- 

 branches seen in higher cortical layers (in lamina III and IV) proves 

 that the stimulus from the other side co-operates with the higher 

 cortical preparation for the bodily function to be innervated. 



Further, " our results point to the [)robability that the neopallial 

 connnissura, the tibres of which originate for a great part in their 

 own cells, has attained a higher degree of differentiation, independence, 

 than the old archipallial, the functioning of which appears in every 

 case to be connected with the working of the projection-libres arising 

 from the same cells. 



That, moreover, among mammals with the constantly developing 

 callosum — in a quantitative respect — there is a qualitatively 

 greater influence of the one hemisphere on the other, is likewise 

 very conceivable. Exen in cat and rabbit it is clear that the result 

 of callosal section can be traced to higher layers of the cortex in 

 the former than in the latter; and these changes must be attributed 

 to the degeneration of the callosal eiidinr/s. 



Now, whereas nothwithstanding this, with the usual methods of 

 investigation of cats'-'), not a trace of any disturbance is to be found 

 some time after the callosal section, we find such often very 

 clearly in man in the case of existing foci of the c. callosum. 



The corpus callosum is in man larger — also relatively — than 

 that of any mammal. And in man also a differentiation with regard 

 to the function of the two hemispheres is first found in mammalia. 



The o-reat functional value of the left half of the cerebrum is 

 seen, for instance, in the fact that with foci of the anterior half of 

 the c. callosum functional disturbances of a high order (apraxia) 

 occur in the left side of the body, which is governed l)y the right 



1) How this is with respect to the pars lenipuralis of the anterior commissura 

 (ventral c. callosum) will, possibly, appear from the dissertation to be made by 

 1. DK Vries in the Central Institute for Brain Research, which will be devoted to 

 the cortex and commissural systems of the mouse. 



-"') And even in monkeys, see Levy— ValeiNSi: Le corps calleux etc. These de l\iris 



1910. 



