HYDROIDEA.. 



rid. 7rin. 



465 



Fia. 701. 



Fresh-wator Polyp, Hydra, two 

 adult specimens attached to 

 aquatic plants; the one oil the 

 left with two younger specimens 

 branching from its side. En- 

 larged. 



20* 



Coral, Millepora alcicornis. 



wonderful experiments made 

 with thorn by Tremblcy, more 

 than a hundred years ago, and 

 essentially repeated by many 

 others in later times. 



Trembley found that whether 

 cut in two, or into many rings, 

 or into longitudinal strips, each 

 part became a perfect animal, 

 lie found that if he split them 

 from the month, part of the way 

 down the body, each section be- 

 came a perfect animal, and that 

 a many-headed hydra was thus 

 produced. And that when he 

 turned them inside out, and 

 compelled them so to remain, 



