HYDRA 



295 



FIG. 75. Hydra. 



A, two living specimens of H. viridis attached to a bit of weed. The larger 

 specimen is fully expanded, and shows the elongated body ending distally in the 

 hypostome (hyp), surrounded by tentacles (f), and three buds (&/!, bd2, bd$) in 

 different stages of development ; a small water-flea (a) has been captured by one 

 tentacle. The smaller specimen (to the right and above) is in a state of complete 

 retraction, the tentacles (t) appearing like papillae. 



B, H.fusca, showing the mouth (mth) at the end of the hypostome (hyp), the 

 circlet of tentacles (/), two spermaries (spy), and an ovary (pvy) 



C, a Hydra creeping on a flat surface by looping movements. 



D, a specimen crawling on its tentacles. (From Parker's Biology : C and D after 

 W. Marshall.) 



hypostome (hyp], at the apex of which is a circular aperture 

 the mouth (mtti). At the junction of the hypostome with 

 the body proper are given off from six to eight long delicate 



