916 
In this case the gut had after the administration of pilocarpin 
reached ultimately such sensitivity that 0.04 mgrms. of pilocarpin 
produced a distinct action within 3 minutes (a). After this the pilo- 
carpin was washed out; then 0.4 cem. of rabbit’s serum was given 
to which a dosis of pilocarpin had been added (6). Thereupon the 
gut evinced large contractions (the magnitude of this deflection is 
immaterial to this investigation). After this serum and pilocarpin had 
been removed by washing, again 0.04 mgrms of pilocarpin was 
given (c), and as appears from the figure the action of this dosis 
was much stronger than before. 
After it had thus been proved that serum is capable of increasing 
the action of-pilocarpin (which in fact was known from our previous 
experiments) we have tried to find out which constituent of serum 
was responsible for this action. To this end we have investigated 
some substances. 
Influence of chotesterin on the sensitivity of 
the cat-gut to pilocarpin. 
In four cases we examined the action of a cholesterin-emulsion 
on the sensitivity to pilocarpin; in all of them the result was positive, 
twice the administration of cholesterin produced a much stronger 
pilocarpin-action than before; once it was distinetly stronger and 
once appreciably stronger. Figs 2 and 3 represent two instances of 
a distinctly increased action. 
After repeated addition of pilocarpin to the polation in which the 
gut had been put (Fig. 2) and then washing it out again, the sen- 
sitivity of the gut had eventually become constant and the gut had 
reached a distinct contraction with 0,1 mgrm. of pilocarpin (a). 
After this pilocarpin had been washed out and the gut had been put 
back again in the vessel of 75 ecm. (which was always used for 
our experiments), 0,2 cem. of cholesterin emulsion was added to 
this vessel (6); the gut did not show any reaction. This cholesterin 
was left in the vessel and then again 0.1 mgr. of pilocarpin was 
added (c). The pilocarpin action is then seen to increase considerably. 
In fig. 3 the course of the experiment was somewat different. Here 
the sensitivity of the fragment of the small intestine was such as 
to show a very distinct reaction on 0.03 mgr. of pilocarpin in 
75 eem. of Tyrode liquid (a). 
It is our custom when the gut has been affected by a poison, to 
transmit it from the 75 ec. vessel to one of 150 cem. capacity, in 
which the poison is then washed out. 
