446 
Summary. 
We have demonstrated in an earlier paper that the isolated small 
intestine yields to salt-solutions quantities of cholin, which are 
capable of stimulating AurrBacH’s plexus. 
This loss of cholin results in a changed behaviour of the gut 
towards atropin. 
The rabbit's small intestine that is inhibited previous to washing 
by small doses of atropin, no longer reacts on them; on the other 
hand it is now stimulated by moderate doses. 
The normal guinea-pig gut is invariably inhibited by atropin. This 
effect also here disappears after washing and is substituted by a 
stimulation through moderate quanta of atropin. 
This is to be interpreted as follows: the real action of moderate 
quanta of atropin on the gut is stimulation of AurrBacH’s plexus; 
if the gut contains much cholin, so that the plexus is readily 
stimulated, this stimulation is arrested through the antagonism of a 
small amount of atropin, occasionally weakened, and the result is 
inhibition. Moderate quanta of atropin are also inhibitory when this 
antagonism is strong enough, but in the presence of small quanta 
of cholin in the gut the latter will be stimulated. 
It is clear, therefore, that here we have to do with a case in 
which the presence of a well known chemical substance (cbolin) in 
the tissue determines the manner in which this substance reacts on 
a poison (antropin). . 
The Pharmalogical Institute of the 
Sept. 1919. Utrecht Uniersity. 
