494 
We did not deem it necessary to show that all the atropin is recovered, be- 
cause — vide supra — most likely, already during the short contact of the 
atropin with rabbit’s serum a small part of the atropin has been destroyed 
chemically. With our method we could not expect to find again all the atropin, 
but what we could show was that the greater part of the atropin could be 
reclaimed in active form. 
This experiment also explains the phenomenon observed by CLOETTA!) and 
SCHINZ *), viz. that they found in their chemical determinations more atropin than 
could be demonstrated physiologically. Now, the chemical reaction (Vitali) consists 
also in extracting with alcohol and chloroform. Scuinz tried to explain it in this 
way that the atropin-molecule was destroyed so far that it could no more react 
biologically, but still gave the chemical reaction. 
The investigation above described was repeated in several other 
experiments, invariably with the same result. | 
In another experiment we astertained whether some further know- 
ledge could be obtained about the quantitative relations in the case 
of adsorption of atropin by rabbit's serum. For this purpose (see 
fig. 2) first 0,1 mgr. of pilocarpin was given and after three mi- 
nutes 0,0002 mer. of atropin; this could neutralize the pilocarpin- 
action almost entirely. In fig. 16 0,1 mgr. of pilocarpin is given 
and subsequently 0,008 mgr. of atropin, which had previously been 
in contact with rabbit’s serum; its action will be seen to be less 
than that of 0,0002 mgr. of atropin, given before, so that apparently 
through the serum the atropin-action had been reduced to ‘/,,. In 
fig. Je again 0,1 mgr. of pilocarpin is administered, then 0,0002 
mgr. of atropin; this could neutralize entirely the action of the 
pilocarpin, from which it appears that the sensitivity of the gut to 
atropin has certainly not diminished during the experiment. The 
atropin given in fig. 25 was taken from a solution which contained 
0.1 mgr. of atropin to 1 e.c. of fresh rabbit’s serum. 
In fig. 2d 0.05 mer. of pilocarpin was given to another piece of 
gut. Its action, as appears from the figure, could be almost entirely 
abolished by 0,0002 mgr. of atropin. In fig. 2e 0,05 mgr. of pilo- 
carpin was given and after this 0,008 mgr. of atropin; this atropin 
had been taken from a solution whieh contained 1 mgr. of atropin 
per c.c. of fresh rabbit’s serum, i.e. 10 times the quantum of the 
previous case. In fig. 17 again 0,0002 mgr. of atropin of the usual 
aqueous solution was given. This experiment then tends to show 
that also when a whole milligram of atropin is added to 1 c.c. of 
rabbit’s serum, the action of atropin is reduced to about ‘/,,. 
1) Croerra. Ueber Angewöhnung an Atropin. Arch. für exp. Path. 64, p. 432, 1911, 
2) ScHiNz Zur angeborenen und erworbenen Atropin Resistenz des Kaninchens. 
Arch. fiir exp. Path. 81 pg. 206. 1917, 
