THE PRODUCTION OF NEW HYDRANTHS IN HYDRA 
BY THE INSERTION OF SMALL GRAFTS 
BY 
ETHEL NICHOLSON BROWNE 
Wirx Six Pirates 
INTRODUCTION 
During the winters of 1906-1908, I carried on some experi- 
ments in grafting Hydra viridis for the purpose of throwing more 
light on the factors concerned in regeneration. ‘The work was done 
at the suggestion of Professor Morgan, whom I sincerely thank 
for his kind interest and help. 
In my first series of experiments, which were done with the 
ordinary green hydra, I tried to discover what material when grafted 
would give ,the necessary stimulus to call forth the develop- 
ment of a new hydranth. It was found by experiment that if a 
tentacle with a small bit of peristome tissue at its base was inserted 
into the body of another hydra, the stock would regenerate a whole 
new hydranth at the place of grafting, the grafted tentacle remain- 
ing as one of the new circlet of tenacles. The question arose 
whether the regeneration was due merely to the presence of foreign 
tissue of any kind or whether it was initiated by some special kind 
of material; and if so, what kind of tissue this was. To solve this 
problem, tissue was taken from different regions of the body of 
Hydra viridis and grafted into different regions of the body of 
other hydras of the same species. 
In my second series of experiments, I endeavored to find out the 
exact origin of the regenerating material. An excellent opportun- 
ity to decide this question was offered by the discovery of Mr. 
D. D. Whitney that the green color can be entirely removed from 
Hydra viridis by putting the animals in a .5 per cent glycerine solu- 
tion and leaving them for about three weeks. These artificial 
Tue JourNAL or ExPERIMENTAL ZOOLOGY, VOL. VIIB NO. I. 
