918 
In the experiment we are going to describe now, 0,5 ccm. of a 
cholesterin emulsion was added in the 150 ecm. vessel, in which 
the gut remained in contact with the cholesterin-emulsion for 
15 minutes and was then washed out. After 15 minutes 
the gut was transmitted to the vessel of 75 cem., and after a 
few minutes again 0,03 mgr. of pilocarpin was poured into the 
vessel, as had been done before (5). From fig. 3 we again see 
clearly that the resulting pilocarpin action is much stronger than it 
had been before. On the basis of these experiments and of others 
proceeding in the same way, we must conclude that the cholesterin 
is capable of increasing the pilocarpin-action, as well when the 
cholesterin and the pilocarpin are added simultaneously to the gut, 
as when first the cholesterin is added, then the cholesterin is washed 
out, and subsequently pilocarpin is administered. This phenomenon 
cannot be considered as an instance of “potentiation” (Büre), it 
being rather a sensibilization of the gut through cholesterin and serum. 
Influence of lecithin on the sensitivity of the cat-gut 
to pilocarpin. 
We now proceeded to find out the action of another constituent 
of serum, viz. lecithin. 
In our first experiments it really appeared that lecithin as a rule 
had a reinforcing influence; afterwards, however, we were able to 
repeat this experiment with very pure lecithin’) prepared from 
brain-substance. It then became obvious that this very pure lecithin 
produced a less constant action than the impure substance we had 
used before. Fig. 4, however, shows again that pure lecithin can 
also intensify pilocarpin action. Here 0,01 mgr. of pilocarpin had 
only an inappreciable action (a). After this pilocarpin had been 
removed, again an equal quantum of pilocarpin was put in the 
vessel holding 75 eem. of Tyrode solution (6) and after the pilo- 
carpin had acted for about 4 minutes, a drop of a 5°/, lecithin- 
emulsion was added, on which the gut immediately reacted by 
strong contractions. After this lecithin plus pilocarpin had been 
washed out again, a drop of lecithin was added to the gut to show 
that of itself this substance bad no effect upon the movements of 
the gut (c); this lecithin was left in the vessel; again 0.01 mgr. of 
1) We wish to acknowledge the kindness of Dr. Levene of the Rockefeller 
Institute in putting at our disposal this lecithin as well as quanta of cerebron 
and other substances to be mentioned lower down. 
Ke 
