This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
These are remedies acting, not essentially and directly on the functions or organs, but on some extraneous body or bodies incidentally present in the system, and operating injuriously upon it. The division embraces the five classes of antacids, absorbents, solvents, disinfectants, and parasiticides, including the subordinate classes of anthelmintics and antizymotics.
It may be objected to the classification here adopted, that the two great divisions are so extremely, one might almost say, so absurdly different in their dimensions. My only answer is, that this is the method of nature; and if I have erred, I have done so in following her footsteps. if the inquirer will look, beyond the science which engages our attention, out into the broader fields of nature, he will observe similar inequalities constantly repeated, both in the physical and the moral world; and will learn in time that, though they may seem discordant when viewed partially, yet the general effect is that of order and beauty. Could our finite capacity embrace the whole, we should undoubtedly find unbroken harmony.