32 



HYDROZOA. 



tliey are able to move from place to place by fixing 

 alternately the extremities of their body after the 

 manner of a leech, and they are sensible to the 

 presence of light, which they always approach. 



But their most wonderful attribute is that of being 

 able indefinitely to reproduce any part of their body 

 which may be cut off. If a Hydra be cut into pieces, 

 each individual fragment, however small, will s-peedily 

 become a perfect animal, in all respects like the 

 original, tlie parts w^hich were defective being pro- 

 duced in their proper situation. If with fine scissors 

 we slit one lialf- way down, the result will be a Hydra 

 with two mouths, each surrounded by the usual 

 number of tentacles ; if these be aofain and asain and 

 again divided, each division wdll become a new head, 

 thus forming a realization of the fable of the Lernean 



Fig. 18.— hvdra vhidis. 



Hydra. Every one of the tentacles of this newly- 

 formed monster will capture food, and all the mouths 

 will devour it. If two be cut across, and the fore- 

 part of one be applied to the hind part of the other. 



