XIII.] THE FROG. 199 



in front of the anterior ends of the kidneys ; 

 their form. 



{3. The ducts of each testicle (vasa efferentia) enter- 

 ing the inner border of the kidney of the same 

 side in order to communicate with the genito- 

 urinary canal (9. a). 



7. Remove the testes: open one and press out 

 some of its contents upon a slide and mount in 

 common water : examine with J objective. 



The spermatozoa: bodies provided with a 

 small oval head and a long vibratile tail in Ii. 

 esculenta : in R. temporaria the oval head is 

 absent : their movements. 



b. In the female. 



a. The ovary: an organ varying much in size 

 with the season of the year. The numerous 

 ova in it. 



/3. The oviduct: a convoluted tube, not con- 

 tinuous with the ovary, and running back to 

 open into the cloaca. The greater part of the 

 oviduct is opaque and glandular ; the part near 

 the cloaca however is dilated, thin-walled and 

 transparent. The oviducts open on the pos- 

 terior wall of the cloaca a little anterior to the 

 openings of the ureters. 



11. The mouth, oesophagus, and respiratory organs, 



a. Open the mouth : note on its roof near the 

 front the two hinder openings of the nasal 

 cavities (posterior nares); farther back, the two 

 larger openings of the Eustachian recesses; the 

 long tongue in the floor of the mouth ; fixed by 

 its front end to the lower jaw; its free, bifid, 

 end turned towards the throat. 



