TRANSACTIONS OP THE SECTIONS. 1 7 1 



of the complete cessation of the sensibility and mobility of the animal, although 

 respiration continues ; and on irritating the eyeball, the eyelids appear to remain 

 sensible. 



4th. The shock, occurring shortly after the immersion, may continue until the 

 respiration of the frog stops, there being little or no return of spontaneous or excited 

 muscular action. 



5th. The shock, observed occasionally when frogs are experimented upon, may 

 disappear shortly after its occurrence and return again afterwards. 



The inquiry into the action of alcohol upon a healthy dog showed — 



6th. That alcohol acts first on the brain, next on the spinal cord, and lastly on 

 the sympathetic system, — a result fully confirmed by the experiments on frogs. 



Results from the second series of experiments. 



1st. When the crural nerves of a frog are cut through ; the animal, having its pos- 

 terior extremities immersed in alcohol, will preserve its sensation and respiration for 

 from fifteen to twenty-three minutes, and consequently for a few minutes longer 

 than when a healthy frog is submitted to experiment. 



2nd. The contact of alcohol with the hind legs of a frog whose crural nerves have 

 been cut, does not give rise to a shock. 



Considering together the results from the first and second series of experiments, 

 it is concluded that the principal channel through which alcohol acts on the nervous 

 centres is the circulation ; but also that the poison exerts a slight influence on the 

 nervous centres exclusively through the nerves. 



Results from the third series of experiments. 



1st. If the abdominal aorta of a frog be tied and its body included within a liga- 

 ture, leaving the crural nerves quite free, the animal, whose hind legs have been im- 

 mersed in alcohol, preserves its sensation and respiration for from four to eighteen 

 hours, while another frog, thus operated on, but not immersed in alcohol, continues 

 feeling and breathing for upwards of twenty-three hours. 



2nd. When the hind legs of a frog, operated on as mentioned above, are placed 

 in alcohol, a shock may occur 



3rd. After having placed a ligature on the thoracic aorta of a dog, the injection 

 of any quantity of alcohol into the animal's stomach produces no sign of intoxica- 

 tion ; while in the case of a healthy dog, as little as one ounce of alcohol (diluted 

 with an equal bulk of water) is sufficient to bring on rapidly symptoms of poisoning. 



4th. Although after the ligature of the thoracic aorta of dogs the injection of alco- 

 hol into the animal's stomach produces no sign of alcoholic intoxication, still a dog 

 thus experimented upon dies sooner than another, who, having undergone the same 

 operation, is not made to take any alcohol. 



These results, considered in connexion with those obtained from the preceding 

 experiments, prove beyond doubt that alcohol acts on the nervous centres principally 

 by means of absorption, and consequently through the circulation, but also that this 

 substance exerts a slight influence on the nervous centres by its contact with the 

 extremities of the nerves, this action hastening the cessation of life without producing 

 any other effect. 



Moreover, the author concludes from his experiments, that whenever alcohol pro- 

 duces a shock, it is due to a peculiar action of the poison transmitted to the nervous 

 centres exclusively through the nerves. 



On the Organs of the Senses, and on the Mental Perceptive Faculties con- 

 nected with them. By W. E. C. Nourse, F.R.C.S., Fellow of the Royal 

 Medical and Chirurgical Society. 



The following are the general conclusions arrived at in this paper. 



1. The organs of the senses, so various in their structure, situations, and functions 

 nevertheless present the most exact analogies with one another, both in structure 

 and function. 



2. Respecting structure, they each consist of two essential parts :— 1st, ^mechanical 



