FUNCTIONS OF DIFFERENT FORMS OF CELLS. 535 
membrane absorb and fix pepsin, they fix it in a somewhat stable 
combination. Such absorption would be comparable to that which, as 
v. Wittieh 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 01 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 King 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 maybe 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 lie 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 
Arch. /. Med.. 
1 Op. cit. 
- Op. cit. 
3 " Untersuch. aus dem 
Gebiete 
der Magenverdauung, 
" Ungar. 
Wiesbaden, 1894, Bd. iii. 
