Thiry in a series of experiments was unable to produce increased secretion of fluid from a Thiry-Vella fistula by the introduction of sulphate of magnesia. He therefore concludes that the action of saline cathartics is due solely to an increase in peristaltic activity. Radziejewski[83] held a similar theory and made many experiments in an attempt to prove that an increase in peristaltic activity was the main result of the administration of a saline purgative. In connection with this it may be noted that van Braam-Houckgeest[84] concluded from his experiments that saline purgatives do not increase the peristaltic activity of the intestine. It is difficult to imagine how these results could be obtained. Hay[85] quotes Aubert, Buchheim, and Wagner as holding the theory that in addition to causing an increased peristalsis, the salt is slowly absorbed, and tends to prevent the absorption of fluid from the intestine. This theory was held also by Schmiedeberg,[86] who claimed that the purgative salts were absorbed with difficulty and reached the lower parts of the intestine unchanged. In the large intestine the salts, according to this hypothesis, prevent the faeces from becoming compact by inhibiting the absorption of water from the lumen. This explanation of the action of cathartic salts has been widely accepted and has been supported by Wallace and Cushny,[87] who claim in addition that the salts of acids which form insoluble compounds with calcium are especially active in inhibiting the absorption of fluids from the intestine. Loeb in studying the action of salts in the production of muscular twitchings in voluntary muscles, and of hypersensitiveness of the skin and nervous elements, recognized the fact that the salts which had these actions included those commonly known as saline purgatives. He says in this connection: “I will not deny the effect of these salts upon the phenomena of absorption of water from the intestine, but it is obvious from our experiments that the same salts must increase the irritability of the nerves and muscles of the intestine, and that this must facilitate the production of peristaltic motions, possibly through the mechanical or contact stimuli of the faeces upon the nerve endings or the muscular wall of the intestine.”[88]