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D. Reproductive Organs and Kidneys. 



1 . The female frog. 



a. The reproductive organs — 



Observe — 



(a) The ovaries suspended by peritoneum in front of the kidneys, 

 the ova projecting from the surface of the ovaries and the fatty 

 bodies from their upper ends. 

 (6) The long convoluted oviducts opening in front by small apertures 

 into the body cavity, and after dilating opening behind into the 

 cloaca. 



Make a diagram showing the ovaries, fatty bodies, and oviducts. 



Make an incision into one of the ovaries, and note that the ova project 

 freely into the central cavity, and that in addition to the mature 

 dark ova (abundant during the breeding season), there are numer- 

 ous, almost colourless, developing ova. Examine a portion of 

 the ovary containing young ova, first with low and then with 

 high power, and draw an ovum showing the vitelline membrane, 

 vitellus, germinal vesicle, and germinal spots. 

 h. The kidneys — 



Observe that they lie in a lymph space behind the peritoneum, and 

 that a simple duct passes from each to open separately into the 

 dorsal wall of the cloaca. 



Make a diagram showing the kidneys, adrenal glands, ureters, and 

 cloaca. 



2. The male frog. 



Observe — 



(a) The kidneys lying behind the peritoneum. 



(6) The testes suspended by peritoneum in front of the kidneys. 



(c) The delicate vasa eflferentia which carry the spermatozoa from the 



testes into the tubules of the kidney. 



(d) The duct (Wolffian) which extends from the outer margin of each 



kidney to the cloaca, and acts both as vas deferens and ureter. 



(e) The vesicula seminalis developed in connection with the outer margin 



of each duct — in R esculenta the vesicula seminalis is represented 



by a simple dilation of the common duct. 

 Make a diagram showing the testes, vasa efferentia, kidneys, common 



ducts, vesiculse seminalis, and cloaca. 

 Cut open the cloaca and look for the openings of the oviducts and 



ureters, and also for the rectal and vesicle openings. 

 Examine (high power; a small portion of testis ; note and draw the 



spermatozoa. 

 Examine again the dorsal aorta, noting especially the branches to the 

 kidneys and genital organs, and its bifurcation into the two iliacs, and 

 then proceed to study the sympathetic nervous system and the 2d to 

 10th spinal nerves and their principal branches. For spinal and 

 sympathetic nerves, see pages 30 and 32. 



