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out in pure Tyrode solution, and the subsequent pilocarpin doses 
had about the same effect (/,g) as before the dialysate was added. 
We call special attention to the circumstance that in this case 
the dialysate of Wirrr’s peptone had an opposite effect to that of 
peptone itself. This is the more remarkable since, in experiments on 
the blood-pressure in the cat to be reported afterwards, we found 
that the adrenalin-action is influenced in the same way by peptone 
and by dialysate. 
We now proceeded to study the influence of Witte’s peptone on 
another poison, viz. cholin. It appeared that the cholin-action was 
the same before and after the addition of peptone. It should be 
noted, however, that the curve showing the relation between the 
concentration and the action of cholin is not by far so steep as that 
of pilocarpin, which means that slight alterations in the dosis of 
cholin have not nearly so much influence upon the contraction of the 
gut as is the case with pilocarpin. It may be, then, that the peptone 
indeed exerts a slight influence in this respect, but that this influ- 
ence does not manifest itself in consequence of the peculiarity of 
cholin just alluded to. 
CONCLUSIONS. 
Here then we have demonstrated that in the serum of various 
animals there occur substances, capable of intensifying the action 
of alkaloids — in this case pilocarpin — on the surviving gut. 
We also found that cholesterin and cerebron also possess this 
property. With lecithin it was doubtful, while peptone acts very 
strongly in this respect and the effect of the peptone-dialysate was 
in an opposite direction. 
When added to a pilocarpin-solution Witte’s peptone appeared 
to inhibit the pilocarpin-action in a small measure, from which we 
may conclude that, like rabbit’s serum, it contains substances that 
are capable of adsorbing pilocarpin. Cholesterin, lecithin and cere- 
bron lack this property. 
From the Pharmacological Institute of the 
University of Utrecht. 
Utrecht, Jan. 1920. 
