CHLORAL AND OTHER NARCOTICS. 499 



understood conditions of disease. It is an equally necessary result 

 that under the continued influence of opium the constantly constringed 

 vessels should assume a new local function ; that nutrition should be 

 arrested in the parts which those vessels supply with blood ; and that 

 the shrunken, impoverished body of the confirmed opium-eater should 

 be an outward and visible sign of the internal changes which are 

 being so assiduously and determinately carried into effect by the nar- 

 cotic. 



When these facts respecting the direct physical action of various 

 toxical agents on the body, through the line of the involuntary ner- 

 vous system, are understood, they connect, through the same direction, 

 the effects of more refined and much less definable influences. They 

 show how psychological phases are ever at hand to modify nutritive 

 changes : how grief, which shocks and dissevers the organic nervous 

 supply, affects the animal life so deleteriously, exciting and reducing, 

 and sometimes in part disabling altogether parts of the organic ner- 

 vous track. They indicate how an equable nervous current is condu- 

 cive to permanent nutritive activity and health, and show physiologi- 

 cally that to laugh and grow fat is after all a mechanical proposition. 

 I must not, however, be tempted away into an inviting field of obser- 

 vation, in which the physical and the metaphysical so neatly blend. 



It is worthy of remark that the action of the different toxicants to 

 which I am directing attention, and which are in most common use 

 among members of the human family, have in some cases a similar 

 action, and in other cases a dissimilar action on the members of the 

 lower creation. The alcohols appear to possess a toxical influence 

 throughout all the domain of living animal beings. I can find no 

 animals that escape the immediate action of the alcohols, or the re- 

 mote effects which occur when the changes excited by the alcohols are 

 often repeated. All our domestic animals come quickly under the 

 ban. Birds and fishes do the same. Chloroform, chloral hydrate, 

 and absinthe seem to exert a similar wide range of action. Tobacco 

 is not so extended in its range. There are animals that can take with 

 perfect impunity a dose of tobacco which would poison three or four 

 men. The goat is an animal which can resist the noxious, but to it 

 innoxious, weed. 



Opium can be resisted by certain animals with equal readiness. A 

 pigeon will practically live on opium. A pigeon will swallow with 

 impunity as much solid opium as would throw twelve adult men into 

 the deepest narcotism. Indeed, it is not correct to say that to pigeons 

 opium is in any sense a poison. 



The reasons for these exceptions are not clearly made out. The 

 probability is, that the animals which take the intoxicants with so much 

 impunity produce some form of decomposition of the agent in their 

 own bodies, by which the active alkaloidal substance is rendered neu- 

 tral in effect, or, at all events, is much neutralized. 



