My own experiments have given quite uniform results, so much so that the production of increased peristalsis in rabbits by the intravenous injection of one of the saline purgatives has come to be a class experiment with the students in the medical school here. The increased secretion into the intestine produced by the same means requires greater care in protecting the loops from loss of heat and moisture. For any one to convince himself that a salt may act as a purgative when injected subcutaneously or intravenously it is only necessary to introduce a small amount of BaCl_{2} into the blood or under the skin of a rabbit. The evacuation of large quantities of semifluid faeces and the violent intestinal movements leave no room for doubt as to the action of the salt. The fact that the intravenous and subcutaneous administration of this salt as a purgative by veterinarians is in general use should be sufficient proof. The milder salts such as sodium citrate and sulphate must, as stated above, be given in larger quantities, and a more prolonged action is necessary. As will be described in detail in the next chapter, the application of solutions of these salts, isosmotic with the blood, to the peritoneal surfaces of the intestine cause not only increased peristalsis and increased secretion of fluid into the intestine but also bring about an evacuation of faeces. This fact alone proves that it is not necessary to introduce the purgative salt into the stomach or intestine. The action on the intestine in this case takes place more rapidly than in any other method of administration. The solution seems to be directly absorbed through the peritoneal covering and to come into contact with the muscles and glands, and perhaps the nerves of the intestine. These tissues are immediately set into activity. In the intravenous or subcutaneous injections of the salts it is necessary to mention a peculiarity of magnesium sulphate. This salt of course acts as a purgative because it is a sulphate and not on account of the presence of magnesium. As shown later on, magnesium chloride has an effect quite opposite to this. In injecting MgSO_{4} into the blood the greatest care must be taken because of its peculiarly poisonous nature when rapidly absorbed. Rabbits frequently die suddenly from an injection of a relatively small quantity. This fact has been mentioned by a number of authors, and is repeated here only as a warning against its too rapid injection, possibly in human beings. It may be mentioned here also that Bottazzi[30] has found that the intravenous injection of an extract of the small intestine containing secretin causes not only a well marked increase in the secretion of fluid into the intestine, but also produces increased peristaltic activity. It at the same time increases the pancreatic secretion. FOOTNOTES: [22] Leçons sur les effets des substances toxiques et médicamenteuses, Paris, 1857. [23] Arch. f. physiol. Heilkunde, 1854.