316 PROPERTIES OF THE COLLOIDAL CONSTITUENTS 



sodium or magnesium salts of acids such as sulphuric, carbonic, phos- 

 phoric, citric or tartaric acids which form insoluble or sparingly dis- 

 sociated compounds with calcium, and their action in stimulating the 

 muscles of the intestine may be regarded simply as an instance of a 

 general effect upon contractile tissues. Barium Chloride, which stands 

 in the peculiar position of not being a calcium precipitant, and never- 

 theless being a powerful stimulant of muscular tissues, is also a very 

 drastic purgative. The inorganic reagents which induce contractions 

 in excised skeletal muscles, therefore, cause purgation when adminis- 

 tered by mouth or injected intravenously. 



Continuing and extending the above-cited investigations of Claude 

 Bernard, J. B. Macallum showed that if 10 c.c. doses of M/6 sodium 

 citrate, sulphate or tartrate be administered subcutaneously to rabbits, 

 followed ten minutes later by 5 c.c., and ten minutes after that by 5 c.c. 

 more, very pronounced purgation follows. Purgation may also be induced 

 by perfusion of these solutions into the bloodvessels supplying a loop of 

 intestine, or even by painting the solution upon the peritoneal surface of 

 the intestine. By whatever avenue the salt reaches the muscular tissue, 

 therefore, contractions are induced. This disposes of the original osmotic 

 theory. The theory of Wagner and Schmiedeberg, that the fluidity of 

 the feces induced by these salts is due to the non-absorption of water 

 from the intestine, was shown to be unnecessary by the discovery by 

 Macallum that part, at least, of the fluidity of the feces is attributable 

 to the active secretion of fluid from the mucous glands of the intestine 

 into its lumen. Thus, a loop of intestine about 30 centimeters long in 

 a rabbit was thoroughly cleaned out by compression and the ends tied. 

 From time to time before and after the administration of a cathartic 

 salt the loop was opened and the content of fluid determined. The 

 following is an illustrative result: 



Loop contained at the beginning . . . . . . . . . . 5.0 c.c. 



Fluid secreted in the first ten minutes 0.2 " 



Fluid secreted in the second ten minutes 0.5 " 



2 c.c. of m / barium chloride injected subcutaneously. 



Fluid secreted in the first ten minutes after injection . . . . 4.0 c.c. 



Fluid secreted in the second ten minutes after injection . . . 3.4 " 



Fluid secreted in the third ten minutes after injection . . . . 3.0" 



the loop after the administration of the barium chloride, also under- 

 went powerful contractions. 



Even when the saline cathartic is administered by mouth, the 

 operative portion of it is that which reaches the intestine through the 

 medium of the circulation, so that even in this instance an osmotic 

 effect of the salt is excluded. This has been very strikingly shown by 

 the experiments of Hertz, Cook and Schlesinger, conducted in Guy's 

 Hospital in London. These observers employed human subjects for 

 their experiments, following the passage of the cathartic down the 

 intestine by simultaneously administering bismuth oxychloride and 

 following the shadow cast by this substance on an .r-ray plate. Sepa- 



