HYDRIDy^.. WJ 



contract itself more and more, and, in doing so, assisted in enlarging 

 the mouth and stomach. I now took in my right hand a thick and 

 pointless boar's bristle, which I held as a lancet is held in bleeding. 

 I approached its thicker end to the posterior extremity of the polyp, 

 which I pressed until it entered the stomach, which it does the more 

 easily since it is empty at this place and much enlarged. I continued 

 to advance the bristle, and, in proportion as it advanced, the polyp 

 became more and more inverted. When it came to the worm, by 

 which the mouth is kept open on one side, and the posterior part of 

 the polyp is passed through the mouth, the creature is thus turned 

 completely inside out ; the exterior superficies of the polyp has 

 become the interior." 



The poor animal would be justified in feeling some surprise at its 

 new situation — disagreeably sujpi'ised, we may add, for it makes every 

 imaginable effort to recover its natural position, and it always succeeds 

 in the end : the glove is restored to its proper form. " 1 have seen 

 polyps," says Trembley, " which have recovered their natural exterior 

 in less than an hour." But this would not have served the purpose 

 of our experimenter. He wished, to know if the polyps thus turned 

 outside in could live in this state ; he had consequently to prevent it 

 from righting itself, for which purpose a needle was run through the 

 body near the mouth — in other words, he impaled the creature by the 

 neck. 



" It is nothing for a polyp only to be spitted," says Trembley. It 

 is in fact a very small thing, as we shall see, for thus reversed and 

 spitted they live and multiply as if nothing had happened. 



" I have seen a polyp," says this ingenious experimenter, " turned 

 inside out, which has eaten a small worm two days after the operation. 

 I have fed one in that state for more than two years, and it has multi- 

 plied in that condition. 



" Having experimented successfully myself, I was desirous of 

 having the testimony of others capable of forming opinions on the 

 subject. M. Allamand was persuaded to put his hand to the 

 work, which he did with the same success I had met with. He 

 has done more, having succeeded in permanently turning speci- 

 mens which had been previously turned, and which continued to 

 live in their re-inverted state ; he has seen them eat soon after 

 both operations ; finally, he has turned one for the third time, 

 which lived some days, but perished without having eaten any- 

 thing, although it did not appear that its death was the result of the 

 operation." 



We have said that the Hydra viridis has neither brain, nervous 



