18 THOUGHTS ON ANIMALCULES. 



IV. 



THE DIVISIBILITY OF VITALITY. 



The most extraordinary vital endowment possessed 

 by the Fresh-Avater Polype, is that of the reproduction 

 of lost parts to an almost unlimited extent, even to the 

 formation of several perfect individuals from the divided 

 parts of a single Hydra. If a polype is cut across trans- 

 versely, the upper part with the arms quickly produces 

 a new body and tail ; and the lower portion as rapidl}^ 

 throws out another body and arms. If the body is slit 

 down longitudinally, and left united at the base, each 

 portion grows into an entire polype, the requisite num- 

 ber of arms shoot out, and two perfect animals attached 

 to one common base are produced ; and, if the division 

 be complete, two free hydra3 are the result. One polype 

 was cut into ten pieces, and each piece grew into an entire 

 animal. If a polype is turned inside out, a transmuta- 

 tion not less wonderful, physiologically considered, than 

 the above process takes place : the original outer surface 

 performs the function of digestion, while the former 

 linino; of the stomach becomes the external inteo;ument 



