593 



motor nerve-fibres are mostly in the lateral columns and the anterior 

 gray cornua. 



3rd. That, in the dorsal and lumbar regions of the spinal cord, 

 these nerve-fibres are in the anterior columns and in the gray matter. 



III. I have shown elsewhere that the transmission of sensitive im- 

 pressions continues to take place after a transverse section of either 

 the posterior, the lateral, or the anterior columns of the spinal cord ; 

 I have shown, also, that after a section of these three columns on 

 the two sides, leaving the central gray matter and a great part of the 

 posterior and anterior gray horns as little injured as possible, the 

 transmission of sensitive impressions continues to take place, al- 

 though diminished. 



Since the publication of my researches on this subject, I have 

 found that the anterior columns contribute positively, though but 

 very little, to the transmission of sensitive impressions. In frogs, 

 in birds, and also in higher animals, I have found that after a com- 

 plete transverse section of the whole of the spinal cord, except the 

 anterior columns, there are traces of sensibility in the parts of the 

 body which are behind the section. During half an hour, sometimes 

 much longer, after the operation, there is no appearance of sensibility, 

 but after a time sensibility becomes evident. It is not to be found 

 everywhere behind the section, but it exists in many parts of the 

 skin. I was for a long time doubtful on this subject, because many 

 times, in examining carefully the section of the spinal cord, after this 

 organ had become very hard from having been immersed several 

 days in alcohol, I have seen that a small quantity of gray matter 

 had been left undivided at the bottom of the wound. But in multi- 

 plying the experiments, I have ascertained beyond all doubt that 

 when the whole of the gray matter has been divided, with even some 

 fibres of the posterior surface of the anterior columns, traces of 

 sensibility could after a certain time be found. 



It has of course been impossible to divide absolutely the whole of 

 the gray matter, without dividing at the same time a greater or 

 smaller number of the anterior columns. In looking at the result of 

 this experiment, and comparing it with that of various others, in 

 some of which very little of the gray matter had been left, while 

 in others the number of the divided fibres of the anterior columns 

 was greater than usual, I have found that in the anterior columns, 



