14 Ethel Nicholson Browne 
tissue will cause the body wall tissue of a normal hydra to change 
its differentiation and function and become tentacle and hypostome 
tissue. 
Part II 
ORIGIN OF REGENERATING TISSUE AND FATE OF ABSORBED TISSUE 
In the second series of experiments, [ tried to find out the source 
of the regenerating material and the fate of absorbed material in 
the foregoing and other experiments. Attempts have been made 
to solve these questions in some cases by grafting Hydra fusca and 
Hydra viridis, a brown and a green hydra, but these attempts have 
proved unsuccessful, for the two species do not graft well. 
Although the graft has been made to stick for a day or so, it always 
pulls away from the stock before any results can be obtained. 
Miss King has attempted to solve the question in her experiments 
by using light and dark green individuals of Hydra viridis. She 
states that she is able to distinguish the two shades for two or 
three weeks, at the end of which time they fuse. In combinations 
between the artificial white hydras produced by Whitney’s method 
and the normal green one the contrast between the tissue of the 
stock and that of the graft is very distinct and remains so for about 
a month. 
Group A 
Regeneration of Hydranth 
In order to determine the exact source of the material forming 
the new hydranth in the preceding set of experiments (Part I), the 
following experiments were done. 
Series | White Tentacle with Base Grafted in Middle of Green 
Hydra 
The result of this graft was in six cases the outgrowth of green 
tissue from the stock carrying the white tentacle with it, and the 
later regeneration of green tentacles (Fig. 42). The new hy- 
dranth material, then, must come from the body wall of the stock, 
while the grafted tentacle remains as one of the new circlet. 
