ACALEPILE. 209 



Seen a mother-polyp which had carried its third generation. From 

 the little one which she had produced issued another little one, and 

 from this a third." 



Charles Bennet, the naturalist of Geneva, says wittily, that a 

 polyp thus charged with all its descendants constitutes a living 

 genealogical tree. 



We have just spoken of turning polyps inside out ! If one of these 

 creatures is thus operated upon while it bears its young on the surface 

 of its body, such of them as are sufficiently advanced continue to 

 increase ; although they find themselves in this sudden manner im- 

 prisoned in an internal cavity, they re-issue subsequently by the mouth. 

 Those less advanced at the moment of reversal issue by little and 

 little from the maternal sac, and complete their career of development 

 on the newly-made exterior. 



The third and most extraordinary mode of reproduction in the 

 polyps has been discovered by Trembley in the case of the green Hydra. 

 So surprised was this naturalist at the strange anomalies which sur- 

 rounded these creatures, that he began to have doubts, and gravely to 

 ask the question, Was this polyp an animal ? Is it a plant ? 



In order to escape from this state of indecision, it occurred to him to 

 cut a Hydra into pieces. Concluding that plants alone could repro- 

 duce themselves by slips, he waited the result of the experiment for the 

 conclusion he sought. On the 25th of November, 1740, he cut a 

 polyp into sections. " I put,'* he tells us, " the two parts into a flat 

 glass, which contained water four or five lines in depth, and in such a 

 manner that each portion of the polyp could be easily observed through 

 a strong magnifying glass. It will suffice to say that I had cut the 

 polyp transversely, and a little nearer to the anterior. On the 

 morning of the day after having cut the polyp, it seemed to me that 

 on the edges of the second part, which had neither head nor arms, 

 three small points were issuing from these edges. This surprised me 

 extremely, and I waited with impatience for the moment when I could 

 clearly ascertain what they were. Next day they were sufficiently 

 developed to leave no doubt on my mind that they were true arms. 

 The following day two new arms made their appearance, and, some 

 days after, a third appeared, and I could now trace no difference between 

 the first and second half of the polyp which I had cut." 



This is assuredly one of the most startling facts belonging to 



