LXELENTEKATA. 



209 



the parasitic animals from various wood-lice and Crustacea, which were assigned 

 by Cienkowski to the fungi, under the name of AmaMdium parcuiticwa, remind 

 us by their reproduction no 

 less of the Grega rinse and 

 their cysts. 

 The Coccidia which we 



ten 

 ill 



^ ::;.> A 



meet with in the cells of 

 the epithelium of the intes- 

 tine as well as in the bile- 

 ducts of Mammalia should 

 also be regarded as Grega- 

 rin<s (fig. 151). They trans- 

 form themselves into egg- 

 shaped zoosperms by the 

 formation of a capsule and 

 the production of several 

 spores from their granular contents. In Coccidium oviforme from the liver of 

 man and of the rabbit there are only four spores formed, which become sickle- 

 shaped rods. 



FIG. 151. Coccidum oviforme from the liver of the rabbit, 

 magnified 550 cliam. (after R. Leuckart). c, d, Stages 

 of spore formation which have only been observed 

 outside the cells. 



CHAPTER VII. 

 CCELENTERATA (ZOOPHYTES).* 



Radially symmetrical animals witli a body composed of cells. They 

 have a body-cavity which serves alike for circulation and digestion 

 (gastrovascular space}. 



Amongst the Coelenterata we meet for the first time with organs 

 and tissues composed of cells. In addition to the external and 

 internal epithelium, cuticular, calcareous, and silicious structures, as 

 well as muscles, nerves, and sense-organs are very generally present. 

 On the other hand, the internal surface of the body is not differ- 

 entiated into organs of circulation and digestion distinct from -each 

 other. The vegetative processes are performed by the internal sur- 

 face of the gastric cavity, the gastrovascular space, of which the 

 central part functions as stomach and intestine, the peripheral as 

 vascular system. 



R. Leuckart was the first to recognise the importance of these 

 characters, and made use of them to separate the Polyps and the 

 Medusae, from the Echinoderms, thus resolving Cuvier's type of 

 Radiata into the types of Ccelenterata and Echinodermata. 



It is only in more recent years that Naturalists have been con- 

 vinced of the close relationship between the Porifera and the Polyps 



* R. Leuckart, " Ueber die Morphologic und Verwandschaftsverhaltnisse 

 nirderer Thiere," Braunschweig, 1848. 



14 



