CHAP. V 



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 (t), and three buds (bd l bd2, b&) 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, (x 6.) 



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

 circlet of tentacles (t), two spermaries (spy), and an ovary (ovy), (x 12.) 



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.) 



apex of which is a circular aperture, the mouth (mth). 

 At the junction of the hypostome with the body proper 

 are given off from six to eight long delicate tentacles 



