442 
away most cases, while at the same time the tonus was more or 
less lowered. 
This is exemplified in Fig. 2. In a few cases the initial inhibition, 
caused by this moderate quantity of atropin, was followed by a 
rather strong stimulation. 
This occurred, when the loops had already been cleaned several 
times, so that the gut had reached a stage, in which the inhibition 
of moderate atropin doses passes into a stimulating action. The next 
day some loops were again severed from the gut which had been 
kept standing during the night in horse-serum at a low temperature ; 
after baving been carefully washed free from the adherent serum 
they were suspended as before. Every ten minutes these loops were 
cleaned with fresh Tyrode solution. One of them (we always took 
the same) was experimented on to ascertain whether 0.01 mgr. of 
atropin still evolved inhibition on the movements. If it did not, the 
other loops of intestine were cleaned again some times and examined 
with regard to their behaviour towards atropin. 
In the great majority of cases it appeared again that a small 
amount of atropin (0,01 mgr.) did not cause the slightest change in 
movements or tonus, but that after administering 15 mgr. of atropin 
a stimulation of the intestinal movements together with a large in- 
crease of tonus was noticeable. See Fig. 3. Over and beyond all this 
the primitive inhibition of the atropin could be elicited again in this 
stage of the experiment, if a small amount of cholin (1—2 mgr.) 
had previously been added to the loops. 
We did not always succeed in reaching this stage already on the 
second day, so that it proved necessary to keep the gut in the 
repeatedly refreshed horse-serum some days longer, in order to arrive 
at a condition in which small doses of atropin do not affect the gut, 
which again had been cleaned repeatedly with Tyrode solution. 
We also succeeded in obtaining this condition by merely cleaning 
the gut with Tyrode solution, i.e. without the appliance of horse- 
serum. It is true, though, that, as mentioned before, the movements 
will become smaller then, and the results less clear. This proves, 
however, that the results are not influenced by horse-serum. 
In the foregoing we have thus shown for the rabbit’s small intestine : 
1st, that repeated washing, which, as demonstrated before, deprives 
the intestinal wall of cholin, evolves a condition in which the initial 
inhibition of small amounts of atropin, is arrested. 
2-4. that by administering cholin this inhibition of atropin may 
be elicited again. 
