Are a sour stomach and foul intestinal canal fit receptacles for food and liquids? When our receptacles are in this condition, why do we add more material for the generation of poisons of the ptomain and leucomain classes, and morbid gaseous elements? It has been demonstrated that during fermentation an apple will evolve a volume of gas six hundred times its own size. What folly then to add to the fermenting mass! Food taken under such conditions will produce results not hard to imagine. The gases that are commonly found in the stomach and small intestines are carbonic acid, nitrogen, oxygen and hydrogen; while, besides all these, sulphureted and carbureted hydrogen are found in the large intestine, causing in a normal state the necessary and useful distention of the alimentary canal. The writer has long regarded the abnormal production of gaseous substances in the intestinal canal from putrefactive changes as of itself not only a grave menace to health, but as a condition productive of morbific results of which we have still much to learn. The more or less constant and excessive distention of the whole or even of a part of the intestinal canal by gases is a serious condition, affecting as it does the various organs of the body, not only through the absorption of these gases into the general circulation but also through the reflex nervous reaction of these organs. It is astonishing what amount of mechanical force is exerted by the gases in the intestinal canal. They distend not only the muscular walls of the intestines and stomach but the strong abdominal walls as well, until the clothing worn has to be loosened for ease and comfort. This more or less extreme mechanical pressure may account for many cases of hernia, prolapse of the uterus, dislocation of various organs, disturbance of the circulation of the blood, and interference with the function of the nervous system, as indicated by its many protests in the way of aches and pains. Naval-constructor Hobson has lately demonstrated the dynamic power of gas confined in bags or receptacles in raising battleships; and it still remains for some physiologist or pathologist to demonstrate the morbid dynamic results of gases confined in the alimentary apparatus. The deleterious effect of the abnormal quantity of gases on all the organs of the body is imperfectly understood at present, but will be better apprehended when we are able to study more minutely the pathogenic poisons of the human system. It is known, however, that a stream of carbonic acid gas, or even of hydrogen, will paralyze a muscle against which it is directed. CHAPTER V. KEY TO AUTO-INFECTION. In a previous chapter we stated that the average quantity of fecal discharge daily, by an adult, is from four to six ounces, and that of this weight 75 per cent is water. We referred of course to the daily passage from the bowels alone, not including that from the bladder.