ELECTROLYTES IN LIVING MATTER 93 



AM 



urea will bring about this effect in a solution, while for KC1 this con- 



111 Wt 



centration lies at - - or . Considering the dissociation of the latter 



4 5 

 solution, these values do not differ very widely. 



I had noticed in my experiments that those salts which produce the 

 abnormal or increased irritability in muscles or nerves are identical 

 with those which are commonly used as purgatives. The action of the 

 purgative salts has been explained by Schmiedeberg and Cushny in 

 this way, that these salts inhibit the absorption of liquid from the 

 intestine, and the excess of fluid in the intestine causes the purgative 

 effect. It seemed to me that the increase in irritability caused by these 

 salts in the muscles and nerves of the intestine must suffice to favor an 

 increase in the peristaltic motions of the intestine, and that this must 

 cause the purgative effect. If this were correct, cathartics should be just 

 as effective if given subcutaneously or intravenously as if given per os ; 

 and moreover, it should be possible to stop these effects by giving cal- 

 cium salts. MacCallum* investigated this point and found indeed that 

 barium salts or citrates, sulphates, fluorides, etc., have cathartic effects 

 if injected under the skin or in the blood vessels. The quickest peristaltic 



Mt 



effects could be produced by applying solutions of these salts to the 



o 



peritoneal surface of the intestine. Application of a solution of CaCl 2 

 or MgCl 2 inhibited these effects. MacCallum found, in addition, that 

 the watery character of the stools in this case is due to an active secretion 

 of fluid into the intestine (and not as had been assumed to a retention 

 of fluid in the intestine). When he isolated an empty loop of the small 

 intestine in a rabbit, it was filled in a short time with a clear liquid, after 

 a series of drops of a sodium-citrate or barium-chloride solution had 

 been applied to the peritoneal surface of the intestine. It was thus 

 possible to obtain in a short time 20 c.c. or more of a perfectly clear 

 fluid from the small intestine of a small rabbit. This secretion of liquid 

 into the intestine could also be inhibited by CaCl 2 or MgCl 2 . 



MacCallum t showed also that the secretion of other glands can be 

 accelerated by the addition of the above-mentioned salts, and can be 

 transitorily retarded by the addition of Ca-salts. The same salts, e.g. 

 BaCl 2 or Na-citrate, which accelerate the secretion of fluid into the 

 intestine also accelerate the secretion through the kidneys, and this 

 acceleration can be counteracted by solutions of CaCl 2 . We have 



* J. B. MacCallum, University of California Publications, Physiology, Vol. i, p. 4, 1903; 

 pp. 115 and 125, 1904. Am. Jour. Physiology, Vol. X, p. 101, 1903; and p. 259, 1904. 

 Pfluger's Archiv, Vol. 104, 1904. 



t MacCallum, University of California Publications, Physiology, Vol. I, p. 8l, 1903. 



