CTENOPHOEA 



88l 



or purple. These spieules are best seen by black-ground illumination, 

 especially when viewed by the binocular microscope. They are, of 



course, to be sepa- 

 rated from the 

 animal substance in 

 the same manner as 

 the calcareous spi- 

 eules of sponges ; 

 and they should be 

 mounted, like them, 



//S^5W c in Canada balsam. 



The spieules always 

 possess an organic- 

 basis, as is proved 

 by the fact that 

 when their lime is 

 dissolved by dilute 

 acid a gelatinous- 

 looking residuum is 

 left which preserves 

 the form of the 

 spicule. 



The Ctenophora, 

 or ' comb-bearers.' 

 are so named from 

 the comb- like ar- 

 rangement of the 

 rows . of tiny 



FIG. 669. 1. Eu-plokamis station is, with its tentacles 

 extended, about twice the natural size: m, mouth; c, 

 ctenophoral plate ; t, tentacular apparatus. (After Chun.) 

 2. Diagrammatic view of Hormijjhora plumosa, seen 

 from the aboral pole : c, as before ; tv, tentacular vessel ; 

 PPt polar plates. (After Chun.) 



FIG. 670. Beroi-' 

 Forskalii, show- 

 ing the ^-tubular 

 prolongations of 

 the stomach. 



' paddles ' by the movement of which the bodies of these animals are 

 propelled. A very beautiful and not uncommon representative of 



SL 



