Isomeric bodies are not only constituted out of the same element, but in the same proportion, and yet they are endowed with the most varied properties. For example, here are starch, gum and dextrine, which have in common the formula of C 12 H 10 O 10; they are all isomerics, but very different substances. Terebene is isomeric with turpentine. The isomeric substances obtained from quinquina, are quinine - which is of great power - and quinidine and quinicine, bdr. G. P. Hachenberg, Cincinnati Medical News, 1880, p. 586.

which are said to be inert. And again, cincho-nidia is almost the equal, perhaps the equal of quinine, while on the other hand, cinchonine and chinchonidine are inert. These substances are isomeric, but the molecular arrangment is differ-ent. In the series of caffeins, there are great differences between the caffein obtained from coffee, and that obtained from tea, from the leaves of the male plant, and from Paultinia. Guaranine is much more active as a diuretic than thein or matein. To comprehend the nature of these bodies, and to explain their effects, it is necessary to take into account structure and dynamization of the substances.