My own experiments which I have described above support this suggestion of Loeb’s. In the first place it was found that the subcutaneous or intravenous injection of one of these salts, especially sodium citrate, caused muscular twitchings in the living rabbit. This had already been done by Loeb in the frog. In both cases the injection of calcium chloride inhibits the twitchings. As shown above, there are produced in a rabbit by such an injection of a purgative salt not only muscular twitchings, but also increased peristaltic movements, and an increased flow of fluid into the intestine. The subsequent injection of calcium chloride was shown to inhibit both the increased secretion and the increased movements of the intestine. There thus seems to be a very distinct analogy between the action of these salts in producing twitchings in voluntary muscles and the production of their purgative effect; and a similar analogy between the suppression of the former and the suppression of the latter by calcium chloride. One is tempted to suppose that these purgative salts act by removing calcium from the tissues, as suggested by Loeb, in the production of muscular twitchings, since they are all calcium precipitants. There is, however, no direct proof of this, and other saline purgatives such as BaCl_{2} and Hg_{2}Cl_{2} certainly have an action which is independent of calcium. There thus seems to be produced by saline purgatives a condition of increased irritability in the intestine analogous to the increased irritability produced in the voluntary muscles. As a result of this the two main activities of the intestine are increased, namely, the peristaltic activity and the secretory activity. The action of the saline purgative, then, as far as we know, consists of two main parts. The peristaltic movements are greatly increased in rapidity and force, and the faeces are carried rapidly from the upper to the lower parts of the intestine. They are thus passed through the large intestine in so short a time that the fluid they already contain has not time in which to be reabsorbed, a process which apparently takes place normally in the large intestine. At the same time there is a much larger quantity of fluid secreted into the lumen of the intestine than takes place in the normal animal. The faeces which are thus forced rapidly through the gut by the increased peristaltic movements are more fluid than normal. This together with the rapid passage of the faeces accounts for their fluid character when a saline purgative is given.