FUNCTIONS OF DIFFERENT FORMS OF CELLS. 535 



membrane absorb and fix pepsin, the) 7 fix it in a somewhat stable 

 combination. Such absorption would be comparable to that which, as 

 v. Wittich pointed out, fibrin exerts when placed in a glycerin solution 

 of pepsin, the fibrin rapidly absorbing the pepsin so as finally to render 

 the glycerin solution inert. The pepsin so absorbed can only be 

 recovered by treatment with hydrochloric acid and not by extraction 

 with water. Finally, Klemensiewicz l and, later, Heidenhain 2 have 

 isolated portions of the pyloric mucous membrane, and observed the 

 secretion thereby obtained. But in Klemensiewicz's experiments the 

 secretion was so mixed with abnormal fluids, such as pus, that the 

 observations cannot be regarded as 'an index of the normal state of its 

 composition. In Heidenhain's observations this difficulty was avoided 

 by the adoption of antiseptic precautions. He obtained a secretion 

 alkaline in reaction, viscous in character, rich in pepsin and rennet 

 ferment. With hydrochloric acid O'l per cent, it digested fibrin very 

 energetically, and caused milk to clot in about a quarter of an hour. 

 Both Klemensiewicz and Heidenhain insist on the strong proteolytic 

 powers of the secretion ; the former even states that it digests fibrin as 

 rapidly as the juice from the mucous membrane of the fundus. There 

 is then a certain amount of disparity between the results of extracting 

 the mucous membrane with various fluids, and testing the proteolytic 

 powers of the extracts and those obtained by observing the peptic 

 strength of the juice secreted by an isolated portion of the pyloric 

 region of the stomach. We must therefore ask which furnishes us with 

 the best criterion of the normal activity of the pyloric mucous 

 membrane ? By extracting with hydrochloric acid a large proportion of 

 the pepsin present in the mucous membrane can ultimately be removed. 

 But Klug 3 finds that, in order to obtain all the pepsin from the pyloric 

 mucous membrane, it is necessary to make at least three successive 

 extracts with hydrochloric acid, each one of the duration of twenty-four 

 hours. The first extract shows little or no peptic activity; the second and 

 third, marked activity. He ascribes the change of activity to the pro- 

 bability that the large amount of proteid present prevents the acid from 

 separating the pepsin from its proteid compounds. But this difference 

 is not found with the fundus, and it is somewhat difficult to understand 

 why it should be more easy to extract the pepsin by acid from the 

 fundus glands than the pyloric. We may regard it therefore as 

 probably true that repeated extracts furnish us with a considerable 

 amount of the pepsin obtainable. On the other hand, it may be asked 

 how far the juices secreted into artificially isolated portions of pyloric 

 mucous membrane are to be regarded as normal ? It seems that in 

 Heidenhain's case there was an absence of inflammatory conditions. 

 But it must be noticed that the operation performed involved very 

 considerable interference with the nerve supply to that portion of the 

 mucous membrane. The mucous membrane was probably, therefore, to 

 some degree in an abnormal condition. Nevertheless, the fact that 

 proteolytic powers were shown could not be explained by reason of 

 such an abnormal state ; they must probably be indicative of normal 

 secretion. It seems impossible that any "infiltrated" pepsin could 

 produce the enduring effect in the secretion noticed by Heidenhain, and 



1 Op. tit. - Op. cit. 



3 " (jutcrsuch. aus dem Gebiete der Magenverdauung, " Ungar. Arch. f. Jfed,, 

 Wiesbaden, 1894, Bd. iii. 



