Page:Popular Science Monthly Volume 15.djvu/513

 the compound in its effect on the living body. Physiological research has not yet reached, by vital analysis of action, a perfection of knowledge on the subject now in hand. Such analysis is yet in its early days. At the same time a general line of research has been made out, and some results have been obtained which are of direct practical value. Other facts have also been elicited which at first sight are surprising, but which lose their singularity when they are correlated with pure chemical physical demonstrations. I found, for example, in one of my researches, that two chemical substances which are isomeric in constitution—that is to say, are composed of the same elementary forms in the same proportions, but under different arrangement—produce entirely different phenomena on the animal body. These isomeric substances are the formiate of ethyl and the acetate of methyl.

The agents used by man for his dreamy delights have thus a varied influence on his nature. They are often rudely classed together as luxuries; but the luxuriousness which they foster may be fathoms wide until they so far interfere with vital function as to reduce its activity in a notable degree. Then there is something in common between them, just as there is something in common when, being carried a little further, they stop life altogether.

For this is interesting respecting them, in the most potent sense. They all kill when we let them have full play. This is obviously the reason why they are called toxicants and intoxicants. They bear resemblance in action to the poison which once in the history of a past civilization sped on the tip of an arrow from a discharged bow.

The toxicants have variation of action in their early stages. Alcohols excite the mind and quicken the pulses before they depress. Opium excites before it depresses. Tobacco does not in the strict sense excite, but depresses and soothes from the first, so that there are stages, which some persons always feel, when alcohol is antidotal to tobacco. Among those persons who are total abstainers from alcohol few are found who can bear tobacco in the most moderate use of it. Under tobacco the heart seems rapidly to run down in power, and alcohol is called for to whip it up again, also as it seems. The fact is, that the heart is not the organ primarily concerned at all, but the minute vessels at the termination of the arterial circuit. These minute vessels are under a nervous influence by which the passage of blood through them is regulated, and which influence is readily modified by very refined causes acting through the organic or emotional nervous centers. The effect of tobacco on these minute vessels, through the nervous system, is to cause contraction of them as a primary fact, so that the face of the person affected becomes pale and the surface of the body cold, while the heart labors to force on the supply of blood until its own vascular system comes under the influence: then the stomach involuntarily contracts, and, after a time, the voluntary