ON THE ACTION OF THE METHYL AND ALLIED SERIES. 1G9 



quick suspeasion both of sensation and consciousness. "We move to the 

 chloride of ethyl, C^ H^ CI, and learn that we have in it still a narcotic 

 capable of producing suspension of sensation and consciousness, like ether, 

 but with this diiference, owing to the introduction of the new element 

 chlorine, that active convulsive movements are superinduced. We turn 

 to the iodide of ethyl, C.^ H. I, to observe again a narcotic action, as with 

 ether, together with irritation and overaction of secreting glands, owing in 

 this instance to the introduction of the element iodine. "We take up the 

 bromide of ethyl, C^ H. Er, to discover an excellent narcotic, but one which, 

 owing to the introduction of bromine, causes dryness of mucous membrane. 

 Lastly, we turn to nitrite of ethyl, C^ H, jS'O^, and experimenting with it 

 learn that with the introduction of the element nitrogen we lose much of 

 narcotic action and gain an agent which, being introduced into the body, re- 

 duces the sympathetic nervous power, lets loose the heart so that it can deliver 

 its blood into enfeebled vessels, allows excreting organs, such as the kidneys, 

 to pour forth an abundant secretion, and which, carried far enough, paralyzes 

 muscular action so efiectually as to overcome even tetanic spasm. 



I point out these simple truths in order to indicate once again the correct 

 line of research in reference to all substances used as medicines. To commence 

 with a base and to follow the modifications of its action through the varied 

 compounds formed upon it, that, as it seems to me, is the only method by 

 which the physiologist can arrive at positive truth in his classification and 

 selection of remedies for the diseases that afflict mankind. 



Direct action of wjents on nervous centres. — The teachings of the last half 

 century have led us to the theory, now generally accepted, that all chemical 

 agents, in order to produce an effect on the body, must enter the blood and 

 be carried by it through the organism. It is ti ue that Dr. Wilson Philip 

 demurred to this, and showed that alcohol would infiuencc the heart imme- 

 diately when brought into contact witli the cerebrum ; and it is also true that 

 Dr. John Jones observed, in his experiments on young alligators, that the act 

 of respiration could be instantly suspended by applying hydrocyanic acid 

 directly to the medulla oblongata. Still the theory remained in force, the 

 argument being that the substances applied to the nervous matter were 

 ra2udly absorbed into the circulation. My own observations on nitrite of 

 amyl have, however, assured me that one agent, at all events, may act directly 

 on nervous matter. To prove this, an animal was allowed to sleep into death 

 in the vapour of bicMoride of methylene, and all the blood-vessels leading to 

 and from the heart were firmly tied, so as to cut off every possibility of 

 circulation of blood into or out of the heart ; then with a subcutaneous 

 injecting syringe, through the o])tic foramen, five grains of nitrite of amyl were 

 introduced into the cavity of the skull, so as to bring the agent in contact with 

 the cerebral mass. Instantly the heart, which had continued pulsating, 

 ceased for a moment, and then recommenced action with the same ex- 

 treme rapidity as is observed in the living animal subjected to the influence 

 of the vapour of the nitrite. I repeated the experiment twice with the same 

 result, the rapid cardiac action continuing from two to three minutes in 

 each case. These experiments lead me to suggest that we have accepted 

 too readily the idea of the necessity of absorption of all chemical substances 

 for the production of physiological effects, and that we ought to go back to an old 

 subject of inquiry, the direct action of chemical and physical agents upon 

 nervous matter. When we irritate the extremities of a nerve, as, for instance, 

 when we inhale strong ammonia or particles of snuff, and excite muscular 

 action, or when we call forth sensation, as when we take in the odour of 



