vi Journal of Comparative Neurology. 



matter what view may be taken of the nature of the processes going on 

 in the cortex, it would seem best to still hold to the view of the sepa- 

 rate localization of areas for the special senses, for motion, and even 

 for muscular and cutaneous sensibility. Lesions of these areas produce 

 phenomena of vision, audition, motion, sensation, etc., which are not 

 produced when the lesions are situated outside of the special areas to 

 which the functions above mentioned are assigned. The fillet radia- 

 tions for cutaneous and muscular excitations, as a compact bundle, 

 probably reach, or most closely approach, the outer layer of the cortex 

 in the postero-parietal convolutions and in the limbic lobe. Whether 

 we should regard the cells and fibers which bring about communication 

 between these regions and the motor cortex as true sensory terminals or 

 as simply constituting a field of conjunction, the only cortical and sub- 

 cortical lesions which will produce pure and marked sensory symptoms 

 will be those occurring in these areas. ' These incoming messages,' 

 says Andriezen, ' which inform the brain of the movement of the limb, 

 arrive ( strictly speaking ) not in the pre-Rolandic but in the post-Rol- 

 andic (ascending parietal) convolutions. In the pre-Rolandic or 

 ascending frontal convolution, and in the adjoining posterior portions 

 of the three frontal convolutions as well as the prolongation of these 

 areas on the mesial ( marginal ) convolution, we find the last term in 

 the cortical series, the finally disposed executive mechanisms.' 



" It would perhaps be best to define the cortical area for cutaneous 

 and muscular sensations, as that part of the cerebrum where the fillet 

 radiations most nearly approach the surface of the brain, before their 

 final ramifications in the molecular layer, still holding to the old view 

 with reference to the motor cortex. Andriezen, as already stated, 

 speaks of the pyramidal and ambiguous cells as the first sensory cells 

 of the cortex, because the terminals of the fillet radiations, or their ex- 

 tensions, first touch the apical processes of these cells, and therefore 

 these cells first receive sensory impressions from the periphery of the 

 body. It would be better, following Forel and Nansen, to disregard 

 entirely the subdivision into cells of sensation and motion, and take 

 the broad ground that we are simply dealing with the greatest and high- 

 est of sensori-motor areas, and that in the region posterior to the area 

 usually recognized as motor, the last stage in the sensory process is 

 reached, while in the Rolandic cortex the first stage in the motor por- 

 tion of the process begins." 



c. J. H. 



