445 
The results obtained by our experiments put us in a position to 
view the variable action of atropin on the gut in a new light and 
to interpret the conflicting results of the various researchers. 
In the living animal cholin is present in the intestinal wall in 
such quantities that they stimulate AverBacn’s plexus. On removal, 
to a certain extent, of the cholin from the surviving gut by a pro- 
longed washing, the real action of atropin manifests itself distinctly. 
According to the earlier experiments of Magnus’) it consists in a 
stimulation of AurrBacu’s plexus by moderate quanta, whereas only 
very large doses paralyse the centra, the nerve, and the muscle. 
Originally the intestinal movements are not affected by small quan- 
tities of atropin. 
It is, therefore, upon the presence of more or less cholin in the 
intestinal wall that the atropin-action depends. 
Cholin has a stimulating effect upon AverBacn’s plexus, which is 
antagonised by atropin. So long as an adequate quantity of cholin 
is present in the intestinal wall, a small dosis of atropin will inhibit 
the cholin action and consequently inhibit the intestinal movements. 
The result of the action of moderate quantities of atropin will 
depend on the circumstance whether the immediate stimulating 
action on the plexus, or the antagonism for cholin preponderates. 
In case the gut contains little cholin the stimulating action comes 
to the front, in case it contains much cholin the antagonism (inhibition) 
predominates. With a moderate cholin-content a stimulation will 
succeed an initial inhibition. 
Likewise we are now enabled to account for the results of earlier 
researches. 
The fact that with the cat’s small intestine the stimulating effect 
of moderate quanta of atropin occurs more often than with the 
rabbit’s or the guinea-pig’s, tallies with our experience that the 
former contains less cholin than the latter two. 
On the other hand it stands to reason that with the guinea-pig gut, 
which was always found to be rich in cholin, the inhibition of atropin 
appears regularly. 
It is obvious now why the isolated rabbit’s gut, according to the 
previous treatment, is now inhibited by atropin, now again is 
stimulated, while on the other hand the intact gut, which could not 
be liberated from cholin by washing, is according to TRENDELENBURG *) 
inhibited regularly. 
1) R. Maenus, Le. 
2) P. TRENDELENBURG, l.c. 
