632 Sergius Morgults 
on the sides of the old part of the animal. While this change 
goes on, the new tissue becomes coated with a brown layer, 
which gets gradually thicker and also darker. [he process con- 
tinues until the color of the cuticula is uniform on both sides of 
the cut surface, so that it becomes difficult, at times even 
impossible, to distinguish the old from the regenerated tissue, 
as shown at(4)onthe figure. The process does not always end 
here, however. The curious thing sometimes happens that 
instead of remaining in this condition of apparent equilibrium, 
the chitinoid covering continues to thicken above the regenerated 
part and to disappear from the old part, so that finally a stage 
is reached, like that shown in (5) of the Fig. 7, which is just the 
A 
3 
Fig. 7 
reverse of the condition found in (1),1. e., the regenerated tissue 
is now covered by a seal-brown layer and the old part has become 
translucent. 
In those few exceptional cases where the worms had no cover- 
ing at all, the new tails also remained “naked.” . The same is 
true of worms treated with a 0.0001 per cent solution of strych- 
nine, in which case the covering disappeared entirely, and none 
was formed over the regenerated tail. | 
This phenomenon, it seems to me, furnishes additional evidence 
in favor of the view that it is the regenerating organism as a 
whole which is engaged in the process of building up the lost 
parts. 
ee 
