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 indivi- 

 dual. 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 peri- 

 toneum to the corresponding kidney, and having con- 

 nected with it a fat-body (cp. ad). From the inner 

 margin of each spermary spring a number of delicate 

 tubes, the efferent ducis (Fig. 61, q), which run in the 

 fold of the peritoneum to the kidney. Entering this 

 organ near its inner edge, they open into a longitudinal 

 tube (L) from which transverse tubes pass horizontally 

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

 milt, or spermatic substance (p. 9). is thus carried off 

 by the same duct as the urine ; the ureter in the male is 



PRACT. ZOOL. 193 Q 



