8 Ethel Nicholson Browne 
tentacles grew out (Figs. 24,25). By further increase in size and 
the formation of additional tentacles, there resulted a double- 
headed hydra, one of whose heads was somewhat longer and larger 
than the other (Fig. 26). 
Result 4. In one case, the grafted tentacle was slowly absorbed 
without any regeneration. 
From the foregoing group of experiments (Group A), it is evi- 
dent that in every region of the body, the graft of a tentacle with a 
bit of peristome tissue at its base may cause regeneration on the 
part of the stock. Moreover, the regeneration in every region 
except in the circlet of tentacles takes the form of a new hydranth, 
of normal size in the anterior and middle regions of the stock, and 
of minute size in the posterior and foot regions. 
Group B 
Two Tentacles with Peristome at Base as Graft in Opposite Sides 
of Stock 
In this set of experiments, I endeavored to find out whether a 
second tentacle with peristome tissue at its base inserted soon after 
the first in the same region of the body on the opposite side would 
cause a second new hydranth to regenerate. In some cases the 
second tentacle was inserted about two hours after the first, and 
in others it was inserted a day later, but both methods gave 
practically the same results. 
Result tr. In two out of six cases, both grafted tentacles caused 
the outgrowth of hydranths. One of these was grafted on March 
20 (Fig. 27); two days later, there was a slight outpushing of the 
body wall of the stock at the base of each tentacle, a new tentacle 
having developed on one of the outgrowths (Fig. 28). On March 
25, the hydra had two quite well developed but small hydranths in 
the middle region, each having two tentacles, a grafted and a 
regenerated one (Fig. 29). The smaller one of these was gradually 
absorbed, till on March 30, no trace of it was left, the hydra having 
only two heads, one with seven tentacles and the other, the regener- 
ated one having four tentacles, one longer grafted one and three 
