Page:Popular Science Monthly Volume 83.djvu/556

552 being sufficient to produce death per kilogram, while, as we have seen, 7.75 grams of ethyl alcohol were required.

But the methyl alcohol of the time of Dujardin-Beaumetz and Audigé, as we now know, was far from pure—hence the failure to gain an accurate measure of its toxicity. To-day that methyl alcohol is produced in greater purity, we should be able to retest the question with greater accuracy. To this we shall soon return.

From the investigations of Dujardin-Beaumetz and Audigé we have, then, our first experimental evidence that while alcohols in large doses are poisonous, not all alcohols are equally poisonous. To them is also due the credit of showing that for the alcohols of fermentation the toxicity is directly in proportion to the molecular weight and boiling point; in other words, that they are in accord with the law of Rabuteau—the higher the molecular weight and boiling point, the greater the toxicity.

Concerning the difficulties confronting investigation in this subject, we have said nothing. Some of these we shall now consider.

Observation has been made by various investigators that different animals react differently to poisonous substances. From this observation arose the discussion as to "the choice of animal" best suited to a study of alcoholic poisoning. Morgan, who had experimented upon the dog, argued that it was the most acceptable animal for work of this sort. Laborde, who, on the other hand, had studied the guinea-pig, urged the use of this animal; while Colin (who had studied neither) was of the impression that the horse or the cow would be more susceptible than either. Daremburg, in considering the discussion, hopefully suggested that probably another contradictor would recommend either the giraffe or the elephant. This in fact might have been the plight had not the work of Joffroy and Serveaux appeared.

Joffroy and Serveaux have shown that while animals differ in susceptibility according to their kind, this difference is relatively constant and usually but slight. The choice of animals thus becomes, in great part, important in so far as one animal rather than another serves better the purpose of this or that investigator.

A question of more than passing importance in the measure of toxicity, however, is the method of administering the substance to be tested. It is a well-known fact that some substances which are extremely poisonous when injected under the skin, for example, snake venom, are in no sense poisonous when given by the stomach. On the other hand, other substances which show slight poisonous effects if given subcutaneously, act with extreme rapidity if added directly to the blood stream. These facts give to the ways and means of injection a high importance.