1 72 FUNCTIONS AND INSTINCTS. 



they detach themselves from the parent stem, 

 and become separate animals. 



It is stated that, by this mode of generation, 

 in the space of a month a single polype may be 

 the parent of a million of descendants. Trembley 

 observed some long branches of trees that had 

 fallen into the water, which he describes as 

 being as full of polypes as a peruke of hairs ; 

 and that though their innumerable arms were at 

 work, there was no confusion amongst them. 



But these animals, as is well known, do not 

 multiply solely by germes, but also by cuttings, 

 as they may be called ; their substance is so 

 instinct with life, that nothing appears able to 

 destroy it a circumstance, perhaps, arising from 

 the nervous molecules of which it seems almost 

 to consist. If divided transversely, each segment 

 will become a distinct animal, send forth ten- 

 tacles round its upper aperture, and close the 

 lower one ; if it is divided longitudinally, each 

 half will form a separate tube in an hour, and 

 begin to ply its tentacles in a day ; even if 

 divided into longitudinal strips, instead of the 

 sides turning in, as in the former case, each strip 

 becomes inflated, and a tube is formed within it : 

 and what is still more wonderful, and seems next 

 to a miracle, these animals may be turned inside 

 out, like the finger of a glove, without destroying 

 either their vitality, their power of producing 

 germes, and of catching, swallowing, or digesting 



