Synthetics. Alkaloids, the result of analysis, are more or less incomplete and uncertain plant representatives. Synthetics are even more uncertain, being the result not of nature's slow but of man's rapid synthesis. This developing branch of chemistry doubtless has a great future before it, and therapeutics will ultimately be much indebted to it. But at present a large proportion of the synthetic products are chemicals whose molecules are held in somewhat unstable equilibrium and are peculiarly liable to disintegration and interchange. For this reason a hopeful conservatism should mark our employment of them. Certain synthetics have become well known; their physiologic actions have been definitely worked out, their in. compatibilities are determined, and their contraindications are defined. These are probably permanent additions to our therapeutic resources. On the other hand, a host of untried and unnecessary ones are arising. We know but little about them, and obtaining clinical data concerning them constitutes more or less of a hazard to our patients. In the day when the people dosed themselves with herbs, even though usually wrongly directed, they seldom worked any positive harm, but now these potent synthetics in lay hands are causing a world of injury.

From the standpoint of this author there are two great objections to the synthetics. First, their lack of stability renders them liable to unaccountable and erratic action due to chemical reactions in the human body not well understood and varying with individual and pathologic states. Of course, this can be said of drugs other than synthetics, but it applies to the former in lesser degree. The objection can be partially met by administering synthetics alone, never combining with other drugs except stimulants and substances destitute of chemical reactions. Secondly, the synthetics seldom act except in the full physiologic dose. Their detailed consideration in this volume will be undertaken to but a very limited extent, confining attention to what is definitely known concerning the safe employment of those better studied and largely employed by conservative prescribers.