490) 
if some precautions are taken which are amply discussed in the 
publication we bave cited. 
The following experiments were made according to this method. 
To the liquid containing a surviving gut (75 cc. of Tyrode 
solution) O,l mgr. of pilocarpin is added. After three minutes 0,0004 
mgr. of atropin is added to the liquid. As may be seen from fig. 
la this dosis of atropin is not sufficient to completely abolish the 
contraction of 0,1 mgr. of pilocarpin. After the atropin and the 
pilocarpin has been washed out, and the gut has been standing in 
fresh Tyrode solution for half an hour again 0,1 mgr. of pilocarpin 
is administered and three minutes afterwards 0,024 mgr. of atropin, 
that is 60 times the quantity given in the previous experiment. This 
atropin had been for 50 minutes in contact with fresh rabbit's serum. 
It will be seen that this quantum of atropin is able to abolish 
the action of pilocarpin; this dosis, then, has a stronger effect than 
the preceding one (fig. 16). 
In fig. 1e first 0,1 mgr. of pilocarpin is given; after this 0,012 
mer. of atropin i.e. thirty times the quantum of the first experiment. 
It is evident that this atropin-action agrees with that of fig. 1a 
Here also the atropin had been previously in contact with rabbit’s 
serum; namely, 1 mgr. of atropin had been added to 5 e.c. of fresh 
rabbit's serum. From these experiments it may therefore be concluded 
that through the contact with rabbit’s serum the action of the atropin 
had been weakened to such an extent that less than one thirtieth 
of the original action is left. 
In fig. 1d again 0,1 mgr. of pilocarpin is added to the gut, and 
three minutes later again 0,016 mgr. of atropin is given. This atropin 
has also previously been in contact with serum; its action is stronger 
than that of 0,0004 mgr. of atropin in fig. 1a. In fig. le again 0,1 
mgr. of pilocarpin is administered and then again the dose of 0,0004 
mgr. of atropin, which had also been given in fig. 1a. 
This experiment serves to show that the sensitivity of the gut has 
not altered considerably; as will be seen the action of 0,0004 mer. 
of atropin is now a little stronger than in fig. 1a. From these 
experiments we may therefore conclude that (see fig. 1d) through 
the contact of atropin with rabbit’s serum its action is reduced to 
one thirtieth, nay, almost to one fortieth. 
Now, in order to prove that this adsorption of atropin by rabbit’s 
serum is not a chemical destruction, but most likely a physical 
process, we proceeded as follows: the atropin-solution, which through 
the contact with rabbit’s serum had lost the greater part of its acti- 
vity, was treated with hydrochloric acid and alcohol, as has been 
