Note 131 — PHARMACOLOGIA. ON THE OPERATIONS OF MEDICINAL BODIES, AND ON THE CLASSIFICATIONS FOUNDED ON THEM.

This is probably the reason of many bodies producing but little effect upon the inferior animals. The vegetable eaters are certainly less affected by vegetable poisons than those animals who exclusively live upon animal substances: it is thus, that a rabbit can take a very large dose of opium without any ill effects, while half the same quantity would poison a dog. It is a curious fact, that a sound horse can take a very considerable portion of opium with impunity, but if he be weakened by previous disease, by strong purgatives, or by excessive bleeding, he is speedily destroyed by a much less dose; (See Bracy Clarke’s Reformed Pharmacopœia for Horses.) In this latter case, does it not appear that the fatal result depends upon the fact of the digestive organs having been disabled, by debility, from effecting that decomposition by which under ordinary circumstances, the drug is disarmed of its potency? What important lights might not be obtained by the institution of a series of well devised experiments upon the comparative effects of medicinal bodies upon man and other animals? The Physiologist has thus availed himself of the resources of the comparative anatomist, and I feel persuaded, that results equally beneficial to science would follow a similar inquiry in relation to the operation of medicines.

In the course of the present work, I hope to shew the truth of this position by some appropriate illustrations.