[3] "In the mean time it may suffice for the physician to know the effects of a medicine when applied to the body, though he knows not the particular manner whereby it acts."—Van Sweiten's Commentaries on Boerhaave, vol. i. p. 394.
[4] "Every branch of study which can at all claim the character of a science requires two things: 1. A correct ascertainment of the data from which we are to reason; and 2. Correctness in the process of deducing conclusions from them."—Whateley's Elements of Logic.
[5] There is no doubt that the small veins which ramify outside the coats of the stomach and intestines are capable of taking up any matters in a state of proper solution, even fats when dissolved in alkali. But are medicines ever taken up by the lacteal absorbents? Probably seldom or never; for it seems that these vessels are only engaged after a full meal, and subsequent to the regular formation of chyle. They do not exist in the coat of the stomach, but commence in the small intestine at some distance from the pylorus.
[6] It may be of some use if I adduce here a characteristic example of each of the great groups of medicines to which I have alluded above:
Class I. Hæmatics.
Div. 1. Restoratives. Iron, in Anæmia.
Div. 2. Catalytics. Mercury, in Syphilis.
Class II. Neurotics.
Div. 1. Stimulants. Ammonia.
Div. 2. Narcotics. Opium.