42S MANUAL OF ZOOLOGY sect. 



The ovaries (Fig. 257, Ov) 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 

 fojg into the ccelom by small 



pj£ . | j] apertures ( Of) placed close 



\ £y| i ,'i M / t0 the bases of the lungs. 



ff\) iSenftej^ ii£c'' Their posterior ends are 



-Cr~^J^^ wM 21l£a%». w '^ e an< ^ thin-walled (Ut), 

 t^iw&W -WW' -isS^C^ 1 an< ^ °P en i nto tne cloaca 

 trn ^3^ ! ^S' iS3Ph^F\\ i-^- The ova break loose 

 GaBagilSQj8£^i^!i. from the surface of the 

 llPiiP^i^lfiflr \ ovary and enter the cce- 



~l — ■^gsSS^mmS? *< T lomic apertures of the ovi- 



„ \WIJKlfBW ducts, the walls of which 



\«lll*/ are gl an dular, and secrete 



yS&)%l an albuminous fluid having 



V J the property of swelling up 



V j in water. The eggs receive 



\\ k a coating of this substance 



,miMk^ as trie y P ass down the ovi- 



1 Wn ducts, and are finally stored 



hjiljl up in the thin- walled pos- 



„ , TT . . tenor portions of those 



Fig. 256 . — Rana esculenta. Urmogemtal r 



organs of the male. Ao, dorsal aorta; tubes, which in the breed- 

 C/, cloaca; Cv, post caval vein ; FK, fat 



bodies; HO, testes; N~, kidneys; i', ing SeaSOIt become im- 

 apertures of ureters into cloaca; Ur, 



ureters. (From wiedersheim's Com- mensely dilated and serve 



parative Anatomy.) 



as uteri. The 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. 



