Coffee interferes with digestion, and, consequently, with nutrition, aside from its specific or general effects upon the digestive organs, by the manner in which it is usually taken: a mouthful of food and then a draught of the beverage prevents the necessity of chewing[89] and prohibits the secretion of the saliva and its admixture with the starchy elements of the cereals and vegetables, so essential to the preparation of this class of food for digestion further on. The first process in the transformation of starch into blood, is its conversion into grape sugar, and we know that saliva fulfills this function; and while it is believed that the intestinal juices also act in the same manner, still, we are not at liberty to suppose that the preliminary change designed to be begun in the mouth is unnecessary. Or, if it be in a measure true that this fluid, being constantly secreted and swallowed, _thus_ performs its legitimate function, it is certain that the salivary glands are injured, their functions impaired, and the quality and quantity of their secretions modified by the ingestion of hot, astringent fluids; and this must certainly be one of the injurious effects of tobacco-chewing or smoking. No one would suppose for one moment that the glands of the liver, or kidneys, for example, could continue their offices satisfactorily in face of constant contact with a poultice of tobacco, corresponding in size to an ordinary quid, which would, in the mouth of a novice, produce purgative effects, often within one minute from its application. In fact, it may be relied upon that the ingestion into the mouth or stomach of any substance that causes the bowels to “act,” in the common understanding of this term, whether the dose be in solid or liquid form——tends to, and the constant or frequent use of such devices will, impair and permanently injure the entire alimentary tract, from mouth to anus, and all its secreting and excreting glands. [Footnote 89: The prevalence of “bad teeth” is in my opinion referable chiefly to three causes: (1) innutrition resulting from the use of impoverished or indigestible food substance, (2) the use of hot drinks, (3) _non-use_ of the teeth; dental exercise is the best dentifrice. Observe the quality, whiteness and clean condition of the dogs’ teeth: from early youth their “tooth-brushes” are bones, which they are constantly gnawing. Bread-crusts, or wheat-kernels, would do the business for our young growing children, replacing “candy,” for instance.]