182 



COLLEGE ZOOLOGY 



Two coiled tubes (nph), which 

 give off a number of ciliated 

 lobules (fl.c}, and enter a 

 bladder (c.v), constitute the ex- 

 cretory system. The bladder con- 

 tracts at intervals, forcing the 

 contents out of the anus. Since 

 the amount of fluid expelled by 

 the bladder is very large, it is 

 probable that respiration is also 

 a function of this organ, the 

 oxygen being taken into the 

 juj animal with the water which 



A B diffuses through the body- wall, 



FIG. 122. Two species of Ro- and the carbonic acid being cast 

 TIFERA. A, Philodina. B, Hyda- O ut with the excretory fluid. 



tina. (From Parker and Haswell, ^r,, , , .. 



after Hudson and Gosse.) The body-cavity is not a true 



coclorn. 



The sexes of rotifers are separate. The female possesses an 

 ovary (Fig. 123, ovy) in which the eggs arise, a yolk-gland (vt) 

 which supplies the eggs with yolk, and an oviduct (ovd) which 



fl.c 



ci 



inlh 



FIG. 123. Diagram showing the anatomy of a ROTIFER. 

 a, anus; br, brain; c 1 , preoral, and c 2 , postoral circlet of cilia ;\ 

 c.gl, cement gland; cl, cloaca; d.ep, dermic epithelium; d.f, dorsal 

 feeler ; e, eye ; fl.c, flame-cells ; int, intestine ; m, muscles ; mth, mouth ; 

 nph, nephridial tube; ov, ovum; ovd, oviduct; ovy, germarium; ph, pharynx; 

 st, stomach; lit, vitellarium. (From Parker and Haswell.) 



