CHAPTER XII. 



THE FROG (continued} : REPRODUCTION AND DEVELOPMENT. 



So far we have considered those parts and organs of the 

 frog which have to do with its welfare as an individual. We 

 have now to consider the organs which are connected with 

 the welfare of the frog as a race, that is, with the propagation 

 of its kind. 



The position of the reproductive organs has already been 

 seen (pp. 23 and 25) : they must now be examined in more 

 detail. The essential part of these organs in each sex is 

 a pair of bodies known as gonads, called in the male 

 spermaries or testes, and in the female ovaries. 



Reproductive Organs of the Male. The spermaries 

 (Fig. 3, r. spy, Fig. 5, spy, and Fig. 7, ts) are a pair of ovoid 

 bodies, each attached by a fold of the peritoneum to the 

 corresponding kidney, and having connected with it a fat-body 

 (cp. ad\ From the inner margin of each spermary spring a 

 number of delicate tubes, the efferent ducts (Fig. 61, ^), 

 which run in the fold of the peritoneum to the kidney. 

 Entering this organ near its inner edge, they open into a 

 longitudinal tube (Z) from which transverse tubes pass hori- 

 zontally across the kidney to open into the ureter (Ur). 

 The milt, or spermatic fluid (p. 9), is thus carried off by the 

 same duct as the urine ; the ureter is therefore often called the 



PRACT. ZOOL. O 



