BEOWX-SEQUARD ON THE CENTRAL NERYOUS SYSTEM. 275 



the sensitive nerves penetrate into the grey matter, such congestion or irritation, as 

 excites in a sensitive nerve itself the most intense pain, could not be conceived to 

 exist without occasioning some sensation. Hence it follows also that reflex move- 

 ments cause no pain nor sensation in the spinal cord, so that, by this observation, the 

 direct ascent of the sensitive nerves in the spinal cord— of which I possess the most 

 satisfactory preparations — is physiologically or pathologically, if we will, confirmed." 



Any one who carefully peruses the foregoing passage will perceive 

 in itself, without reference to other contradictory portions of the 

 book, the insufficiency of Professor Schroeder van der Kolk's argu- 

 ment as regards the physiological properties of the spinal marrow. 

 In the main it comes to this ; the grey matter is itself not sensitive, 

 it is therefore inconceivable that it can conduct sensitive impressions : 

 or again, a nerve which conveys sensitive impressions is itself very 

 sensitive to pain, the grey matter is not sensitive to pain, therefore 

 it cannot convey sensitive impressions. There is not the least ground 

 for admitting such an inference ; to be sensitive to pain and to be 

 capable of conveying sensitive impressions are distinct functions, not 

 of necessity co-existing in the same parts of the nervous system ; be- 

 cause they co-exist in the nerves of the trunk and limbs, it does not 

 follow the same should necessarily be the case in the grey matter ; it 

 certainly cannot be granted as an assumption, indeed several consi- 

 derations lead one to the very reverse conclusion. We know for in- 

 stance that the optic nerve, which undoubtedly conveys impressions 

 received from light, is itself not sensitive when cut or punctured, or 

 at least, if sensitive at all, very slightly so : we have ourselves known 

 of a case in which the optic nerve was, by a curious accident, punc- 

 tured ; there was instant loss of vision, but no pain referrible to the 

 optic nerve, nor was the sensation of a flash of light, said to follow 

 the lesion of this nerve, perceived by the individual. Until, there- 

 fore, Professor Schroeder van der Kolk adduces some facts in support 

 of his assumption, his argument cannot be admitted to have any real 

 value. 



With reference to the decussation of sensitive impressions in the 

 spinal marrow and the determination, with precision, of the exact seat 

 of this decussation, we think the experiments of Dr. Brown- Sequard 

 lead to conclusions, if possible more definite, than any of his other re- 

 searches. It has been known, indeed, for centuries, that the conductors 

 of sensitive impressions, as well as those of the impulses of the will 

 to muscles, decussate somewhere in the cerebro-spinal centres, but 

 Sir Charles Bell seems to have been the first physiologist who under- 

 took the attempt to determine the real situation of the decussation of 

 sensitive conductors; though he gives no experimental proofs whatever 

 of his idea, which was that the crossing took place in the floor of the 

 fourth ventricle, above and very close to, the decussation of the anterior 

 pyramids. Sir Charles Bell was so fond of making systematic plans 

 for himself, that he seems to have been thus led to adopt, on very 

 insufficient grounds, an idea which suited his imaginary scheme. He 



