90 TREMBLEY'S EXPERIMENTS UPON HYDRA. 



of the many-headed monster of olden time. Yet the inge- 

 nuity of Trembley was by no means exhausted ; for seeing that 

 these little creatures were mere sacs, the idea of turning them in- 

 side out struck him as a feasible one, and he therefore proceeded 

 to the experiment with a great deal of care and perseverance, as 

 his detailed account of his method of performing the act seems 

 to show. With the help of the blunt end of a fine needle he 

 pushed the bottom of the sac through the body and out of the 

 mouth ; but he found that the animal righted itself as soon as 

 left alone again, and therefore, after having again succeeded in 

 the inversion, he ran a bristle crosswise through the body, and 

 thus compelled the little victim to retain its change of front, and 

 reorganize its internal and external departments. This it did 

 not seem to have any difficulty in accomplishing, after the lapse 

 of a few days, as Trembley proved by presenting it with bits of 

 meat, which it swallowed with accustomed voracity. 



Trembley now undertook to ingraft one individual upon 

 another; and this he succeeded in doing after some curious 

 experiences. At first he pushed the tail of one individual deep 

 down into the cavity of another, and in order to hold them 



in this position he ran 

 a bristle through their 

 bodies, (fig. 46, A,) and 

 tied a knot in the end 

 which was below the 

 surface of the water to 

 prevent the spitted pair 

 Flg ' 46> from leaving their post. 



But the simple Hydras outwitted their tyrant, who, to his great 

 amazement, found them, some hours after, hanging side by side, 

 (fig. 46, B,) as if they had never been under more intimate rela- 

 tions. He concluded, then, to watch the next pair, when he dis- 

 covered that the inner one first pushed its tail through the hole 



Fig. 46. Hydra fusca. Trembley. Twice natural size. A, two hydras 

 ensheathed one by the other, and a bristle run through them. B, the same as 

 A, separated from each other, but still spitted by the bristle. From Trembley. 



