I2O THE OCEAN WORLD. 



anterior extremity of the young animal ; the posterior extremity by 

 which it is attached to the mother contracting by degrees, until it 

 appears only to touch her at one point. Finally, the separation is 

 effected, the parent and the young acting in concert to produce the 

 entrance of this interesting young polyp into the world. Each of 

 them take with their head and arms a strong point of support upon 

 some neighbouring body ; and a small effort suffices to procure the 

 separation; sometimes the parent charges herself with the effort, 

 sometimes the young, and often both. 



When the young polyp is separated from the parent, it swims 

 about, and executes all the movements peculiar to adult animals. 

 The entrance into life and maturity takes place with these beings at 

 one and the same moment. Infancy and youth are suppressed in 

 this little world. 



In the course of his experiments Trembley found the following 

 remarkable fact. 



Upon a young polyp still attached to its parent he observed 

 a new polyp or polypule, and upon this unborn creature was 

 another individual. Thus, three generations were appended to the 

 parent, who carried at once her child, her grandchild, and great- 

 grandchild. 



" In observing the young polyps still attached to their parent," 

 says Trembley, " I have seen one which had itself a little one which 

 was just issuing from its body; that is to say, it was a mother while 

 yet attached to its own parent. I had in a short time many young 

 polyps attached to their parents which had already had three or four 

 little ones, of which some were even perfectly formed. They fished 

 for woodlice like others, and they ate them. Nor is this all. I have 

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

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

 from this a third/' 



Charles Bennet, a 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 01 

 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 

 imprisoned in an internal cavity, and 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. 



