4--S 



MANUAL OF ZOOLOGY 



The ovaries (Fig. 257, Or) are large folded sacs, on the 

 surface of which the black and white ova project. A fat- 

 body is attached to each. The oviducts (Od) are greatly 

 convoluted tubes, the narrow anterior ends of which open 



into the ccelom by small 

 apertures ( Ot) placed close 

 to the bases of the lungs. 

 Their posterior ends are 

 wide and thin-walled ( Ut) , 

 and open into the cloaca 

 (P)- The ova break loose 

 from the surface of the 

 ovary and enter the cce- 

 lomic apertures of the ovi- 

 ducts, the walls of which 

 are glandular, and secrete 

 an albuminous fluid having 

 the property of swelling up 

 in water. The eggs receive 

 a coating of this substance 

 as they pass down the ovi- 

 ducts, and are finally stored 

 up in the thin-walled pos- 

 terior portions of those 

 tubes, which in the breed- 

 become 



season 



1m- 



Fig. 256. — Rana esculenta Urinogenital 

 organs of the male. ,-h\ dorsal aorta; 

 CI, cloaca, CV, postcaval vein; FK, fat . 

 bodies; HO, testes; .V, kidneys; 5, lllg 

 apertures of ureters into cloaca; Ur, , 1 



ureters. (From Wiedersheim's Com- mensely dilated and Serve 

 fiarative Anatomy.) . _, . . , 



as uteri, lhe eggs are laid 

 in water in large masses ; each has one black and one white 

 hemisphere, the former always directed upwards, and is sur- 

 rounded by a sphere of jelly. During oviposition the male 

 sheds his spermatic fluid over the eggs, and the sperms 

 making their way through the jelly impregnate them. 



