3. _The Process of Digestion_ has also been learned solely by experiment. In the history of science there are two or three cases of individuals in whom a wound or an operation has produced a gastric fistula, that is to say an abdominal opening through which the stomach can be reached and food introduced. Had we remained satisfied with these accidental observations, we should have obtained but mediocre results. Physiologists therefore have made experimental gastric fistulæ. Dogs thus operated on, after an illness of a few days, recover thoroughly. Some physiologists have kept dogs for several years in this condition: gay, caressing, docile, they did not appear to complain of their lot. They were better nourished, more petted and loved than the many starving dogs which roam about the country. They were not a whit more unhappy than was Alexis St Martin (observed in 1831 by Dr Beaumont) and Marcellin (whom I observed in 1878, at the beginning of my career). Quite recently an eminent Russian physiologist, Pawloff, has, by making gastric fistulæ in animals, been able to discover a number of important facts, absolutely necessary to be known for the treatment of diseases of the stomach, and even for the establishment of a normal alimentation. The problem of alimentation is, indeed, one of the most essential, perhaps the most essential, in the history of humanity. I suppose that anti-vivisectionists are aware of the fact that, even in Europe, large populations exist who are insufficiently nourished. Under these conditions, is it not desirable to know exactly the quantities of carbon, nitrogen, salt, lime, and phosphorus which are necessary for animals, and consequently for man? Should not anti-vivisectionists, interested in vegetarianism, before venturing to institute a vegetable diet for man, try it first of all upon carnivorous animals, so as to know how a mixed alimentation can be modified by a vegetable alimentation, and to what extent those modifications are compatible with health?