ON THE CEREBRO-SPINAL, NERVES. 271 



course of my investigations, I have frequently had 

 occasion to observe the fact.* 



In the few surgical cases where it has been deemed 



O 



necessary to tie the abdominal aorta in the human 

 subject, a similar effect has also been recorded. It 

 was at first thought that the accidental retention 

 within the ligature of some filaments of the aortic 

 plexus of ganglionic nerves was the cause of the 

 paralysis. But there can be no doubt that this 

 explanation was fallacious, and that the paraplegia 

 was simply the result of the cessation of the blood's 

 motion in the minute vessels of the nerves of the 

 affected limbs. For, as detailed in the experiments 

 above referred to, and which are the more reliable as 

 they were undertaken with another object, I have 

 invariably found the connection between the stoppage 

 of the circulation in the part and the production of 

 the paralysis to be uniform and instant. On simply 

 compressing the aorta with a forceps, the limbs 

 receiving their supply of blood from it were at once 

 deprived of sensation and voluntary motion. On 

 allowing the blood again to flow into the femoral 

 arteries, the animal within a few seconds regained 

 the power of moving the hinder extremities, and 

 " suddenly sprung up with a bound." In fact, the 

 cessation and restoration of the sensorial functions of 

 the nerves of the hinder extremities were, in these 

 experiments, seen to be as clearly dependent on the 

 presence or absence of the streams of arterial blood 

 in the vessels of the part, as the action of a fountain 



* Vide ante, Experiments on the Kidney, pp. 47, 48. 



