196 ANNUAL OF SCIENTIFIC DISCOVEEY. 



dorsal vertebras were now removed, and the spinal marrow laid bare 

 for about two inches of its length. It was then found that the ante- 

 rior and posterior columns of -the cord, and the anterior and posterior 

 roots of the spinal cord, could be pricked, seized with forceps, and 

 pinched or pulled, without eliciting any symptom of sensibility or 

 muscular convulsion. The paralysis of the spinal nervous system 

 was found to be complete. The animal was then let alone for four 

 hours, and at the expiration of that period, the alcoholic lethargy 

 having considerably subsided, the same excitatory manipulations were 

 resumed, and the cord was found to have regained its normal suscep- 

 tibility, as proved by the appearance of the physiological manipula- 

 tions usually attendant upon the employment of local stimulation. In 

 order to ascertain the physiological effects of carbonic acid, the fol- 

 lowing experiment was performed : The same process of vivisection 

 having been accomplished, namely, the removal of the arches of 

 the last three dorsal vertebrae, the animal was made to inhale a 

 mixture of carbonic acid gas and watery vapor, and at the end of ten 

 minutes became quite motionless and senseless, the arterial blood hav- 

 ing assumed a dark venous hue. It was then found that the posterior 

 columns of the cord, and the posterior roots of the spinal nerves, 

 could be pricked, pulled, or pinched, without the production of any 

 sign of sensibility on the part of the animal ; but that if, on the other 

 hand, an anterior root were pricked, or the anterior column of the 

 cord stimulated, convulsive movements were produced in the dog's 

 hind quarters; moreover, that if the sciatic nerve were bared by 

 incision and irritated, the muscles to which it is distributed were 

 immediately thrown into a state of spasmodic contraction. la other 

 experiments oxide of carbon was substituted for carbonic acid with 

 the same results. The deductions drawn by these physiologists from 

 their recent course of investigation tend to establish the fact that 

 alcohol, chloroform, and their "kindred spirits," act primarily on the 

 nervous centres by their actual presence icithin the nerve-substance; 

 whereas the carbonic gases act primarily on the blood only, by the 

 conversion of the arterial into venous blood ; the difference of their 

 modes of action being that in the first case the anaesthesia is direct 

 and primitive, and due to the immediate action of the toxical agent 

 on the nerve matter ; in the second, it is indirect and consecutive, 

 depending on the action of the modified blood upon the nervous 

 centres. Comptes Rendus. 



ACTION OF CHLOEOFOEM. 



The action of chloroform has been attributed by the majority of 

 writers to a special electric affinity for the nervous system with which 

 it is brought in contact by the circulation a direct power of para- 

 lyzing, in a greater or less degree, the various functions of the brain. 

 The researches of Faure and Gosselin have deeply shaken this 

 hypothesis. The late Dr. Snow was impressed with the notion that 

 the insensibility produced stood in direct relation to imperfect oxy- 

 genation of the blood. The subject has been investigated by Dr. A. 

 E. Pouson, late of the King's College Hospital, who gives as his con- 

 clusions, in a paper read before the Medico-Chirurgical Society, 



