72 OUTLINES OF CHORDATE DEVELOPMENT 



tissue, filled with drops of fatty substance chemically similar 

 to the deutoplasm of the eggs. These are larger and more 

 abundantly supplied with fat just prior to the breeding season. 

 Their function seems, in part at least, to supply the material 

 used in the final stages of the growth and maturing of the eggs, 

 and also possibly, though doubtfully, for the nutrition of the 



ao 



FIG. 24. FIG. 25. 



FIG. 24. Urinogenital system of the female frog. After Wiedersheim 

 (Ecker). c, Cloaca; k, kidney; o, ovary; od, oviduct; oo, opening of oviduct 

 into cloaca; ou, opening of ureter into oviduct; ut, uterus. 



FIG. 25. Urinogenital system of the male frog. After Wiedersheim (Ecker). 

 ao, Dorsal aorta; c, cloaca; /, fat body; k, kidney; ou, opening of ureter into 

 cloaca; t, testis; u, ureter; -o, vena cava. 



animals themselves prior to and during the spawning season, 

 for usually no food is taken after the end of their period of 

 hibernation till after spawning is completed. 



The remaining parts of the female reproductive system are 

 the oviducts (Miillerian ducts). These are a pair of very 

 long, much convoluted tubes, of small diameter but with 

 rather thick walls, suspended from the dorsal body wall by 



