628 Sergius Morgulis 
In Table XX, referring to an experiment with digitalin in a 
concentration I: 1,600,000, it will be observed that the number of . 
regenerated segments varies from 3 to 4, the former ones pre- 
dominating. In the control of this experiment the number of 
regenerated segments varied from 3 to 5, and 4 was the predomi- 
nant number. So that in this case, as also in the concentration 
of 11,000,000, the rate of regeneration was decreased. In 
Table XXI are given the results of an experiment with digitalin 
in a concentration of 1 : 3,200,000. The number of regenerated 
segments varied from 3 to 6, while that of its control varied only 
from 2 to 4. Not only has the number of segments regenerated 
been greater in this solution of digitalin than in normal sea- 
water, but the regenerated tails themselves were larger. 
If we compare all the data from experiments with digitalin, it 
will be found that solutions of this reagent may exert either a 
highly toxic effect, killing the animals, or it may exert a retarding 
or a stimulating effect or none at all, depending upon its concen- 
tration. The limit of toxicity lies somewhere between concentra- 
tions I : 800,000 and 1 : 1,000,000; the lower limit of its effective- 
ness being somewhere in the neighborhood of 1 : 10,000,000, 
while in concentrations I : 1,000,000-I : 2,000,000 it is depressing, 
and in concentrations I : 3,000,000-I : 4,000,000 it is stimulating 
in its action. 
Third Series of Experiments 
In this series of experiments was investigated the effect of 
other alkaloids, such as strychnine and pilocarpine, upon the 
rate of regeneration. Solutions of 0.001 per cent of either strych- 
nine or pilocarpine proved extremely toxic to the worms, all of 
which invariably died in these solutions. It may, perhaps, not 
be amiss to mention here that the worms were not killed by these 
solutions immediately, but that they continued to live in them 
for 6 to 7 days. The poisons, however, affected the worms in 
a curious fashion. In all of the worms the intestines became 
everted and thrust out through the mouth. None of these worms 
ever regenerated. Even in the much more diluted solutions 
worms were occasionally found that were affected in a similar 
