ON THE CEREBRO-SPINAL NERVES. 269 



anatomically connected with the brain and spinal 

 cord, it will continue to transmit impressions to and 

 from these centres of nervous action. Now these con- 

 clusions are, doubtless, in a great measure, correct, 

 as regards the transmission by the nervous fibres of 

 motific or spinal impressions. For we find that in 

 the bodies of animals recently killed, and after the 

 circulation has entirely ceased, extensive spasmodic 

 movements may be induced by irritating the spinal 

 cord. But it appears to me, that the transmission 

 by the same nerves of purely sensorial impressions, 

 or those productive of sensation and voluntary motion, 

 is accomplished under totally distinct conditions, and 

 regulated by other and more essentially vital require- 

 ments than those above-mentioned. And I shall 

 accordingly attempt to prove 



1. That a constant supply of arterial blood to the 

 minute vessels of the cerebro-spinal nerves is required 

 for the proper performance of their sensorial functions. 



2. That local disorders of the circulation, affecting 

 the blood-vessels of the nerves, are followed by corre- 

 sponding irregularities in the transmission of the im- 

 pressions of sensation and volition to and from the 

 brain. 



And as corollaries from these laws, the following; 



* O 



propositions may be deduced, viz. : 



1. That the white or fibrous portion of the brain, 

 which is identical in structure with the cerebro-spinal 

 nerves, also, like them, requires for its nutrient 

 vessels an incessant and normal supply of arterial 

 blood in order to enable it to conduct impressions 

 to and from the gray matter of the organ. 



