612 SHEINA MARSHALL 



the Hydra can recover if removed to pure water. The 

 chloroform has, however, a macerating effect, which begins to 

 act at the tentacles. 



Chloretone . — The effect of this was to make the Hydra 

 throw out masses of endodermal cells by the mouth. It 

 usually died. 



Cholin. — Weak solutions (1 : 1,000) of this were used but 

 were ineffective. Stronger solutions led to a half -contracted 

 state, but the animal soon recovered in fresh water. 



Curare. — A weak solution of curare was prepared by 

 grinding up 0-1 grm. curare with 20 c.c. water and filtering. 

 A clear yellowish solution was obtained. A Hydra was put 

 m a small dish and this solution added till it was about half 

 strength. For some hours the Hydra remained quite 

 normal. After that a stimulus on any part of the body was 

 responded to by a general contraction, and the tentacles 

 remained half contracted. It was left in the solution over 

 night and in the morning was found to have eaten a D a p h n i a 

 which had been present ; but it was very much contracted 

 and did not respond at all to stimulation. Eemoved to fresh 

 water it expanded but remained very insensitive. On examina- 

 tion the tentacles were found to be degenerating from their 

 tips downwards. 



The experiment was repeated with another Hydra and 

 the same result obtained much more quickly, for in two hours 

 the animal ceased to react to stimulation and its tentacles 

 began to degenerate. 



It is noteworthy that necrosis always begins at the tentacle 

 tips and works down gradually, the body remaining apparently 

 normal for some time after the tips of the tentacles have 

 disappeared entirely. 



In one case the whole head suffered necrosis and the animal 

 remained as a closed tube for some days. It then produced 

 two buds about the middle of the body and a third near the 

 head region but slightly to one side. These developed and 

 constricted off and a fourth bud appeared, again to one side 

 of the head. As it developed it swung round so that eventually 



