Production of New Hydranths in Hydra 3 
of the body. In this way I inserted a tentacle with a small bit 
of peristome tissue at its base in different regions of the stock 
hydras with varying results. 
Series I Graft Made in Middle of Stock 
Result r. ‘The usual result following the graft of a tentacle with 
a bit of peristome tissue at its base into the middle region of a hydra 
was the outgrowth of a new hydranth from the region of graft, the 
grafted tentacle persisting as one of the new circlet. The result 
can be best shown by a specific instance. 
On February 19, a tentacle with peristome tissue at its base was 
grafted in the middle of the body of a healthy green hydra. After 
a few hours, the wounded surfaces had healed and there resulted 
a hydra perfectly normal except for the protrusion of a tentacle 
from the middle of its body (Fig. 1). Onthe next day, a slight 
outpushing of the body wall around the tentacle was observed. 
On February 21, two days after operation, this outpushing could 
be distinctly recognized as a new hydranth. ‘The new hydranth 
consisted of a short body protruding from the body of the stock, 
having at its distal end the large grafted tentacle and three very 
short tentacles (Fig. 2). On the following day these new tentacles 
were distinctly longer but not so long as the grafted tentacle. 
On February 23, the fourth day after operation, a small fifth 
tentacle had appeared and the grafted tentacle was still distinctly 
larger than the regenerated ones (Fig. 3). The difference in 
length of the tentacles was gradually lost by the further growth of 
the regenerated ones until on February 28, the hydra appeared as 
a double-headed hydra, one head bearing six tentacles and the 
other, the regenerated head, five; the original head was still con- 
siderably longer than the regenerated one (Fig. 4). That this 
new hydranth was functional and similar in all respects to the old 
hydranth was proved by the fact that it could capture and ingest 
food with as great ease as the oldone. ‘This double-headed hydra 
remained in the condition described without further elongation of 
the new hydranth until it died on March 14. Similar results have 
been obtained in ten other similar grafts. In some cases, how- 
