Production of New Hydranths in Hydra 15 
Series [11 White Tentacle with Base Grafted in Foot of Green Hydra 
The result of this graft was in four cases the outgrowth of a 
small amount of green tissue at the base of the white tentacle to 
form a minute hydranth (Fig. 43). This pinched off as a small 
green hydra with one white tentacle (Fig. 49). Four days after 
operation a second tentacle appeared on it, composed of green 
tissue; some of the white material of the grafted tentacle seemed 
to have been absorbed into the anterior part of its body (Fig. 50). 
From these experiments the conclusion must be drawn that it is 
principally the material of the body wall of the stock and not the 
hydranth material of the graft that forms the new hydranth. The 
ectoderm and endoderm cells that have been body wall cells are 
therefore changed over into cells composing tentacles and hypo- 
stome. 
Group B 
Absorption 
In order to find out the fate of the material grafted into the stock 
hydra when no regeneration took place; whether the material was 
incorporated into the tissue of the stock hydra, or whether it was 
so absorbed that it no longer existed as such, the following experi- 
ments were performed. 
Series [ Green Tentacle Without Base Grafted into White Hydra 
As the green tentacle was absorbed, the green material spread 
along the body wall of the white hydra for a small area at the union 
of stock and graft (Figs. 44, 51). The two hydras on which the 
experiment was performed were unfortunately lost before com- 
plete absorption. But it was evident that the green tentacle 
material was being transformed into body wall material and incor- 
porated in the stock. 
Series If Green Circlet in White Hydra 
After the graft of a green circlet of tissue from a normal hydra 
into the middle region of the body of a white hydra, this tissue 
remained in the white body as a patch of green (Fig. 45). 
