THE VERTEBRATE BODY 



355 



beings we find quite a number of differences. Since the frog depends on 

 water for transference of the sperms to the eggs there is no male copula- 

 tory organ. In man, however, the eggs are fertilized internally and the 

 male has a copulatory organ, the penis, which is used for this purpose. 

 The testes are in a different position in man ; they are suspended outside 

 the body in a scrotum, for it seems that human sperms cannot develop in 

 the high temperature found inside the body cavity. Occasionally the 



Uterus 

 Urinary bladder 



Vagina 



Clitoris 



Urethra 

 Labium minus 



Labium majus 



Fig. 24.6. The female reproductive system. 



testes remain in the body cavity in man. An individual with this con- 

 dition is almost always sterile, but may become fertile if the testes are 

 brought down through the inguinal canal into the scrotum by a surgeon. 

 The vasa efferentia pass into a structure that partially envelops one side 

 of the testis ; this structure is known as the epididymis. From this the 

 sperms pass into the vas deferens (pi. vasa deferentia) which runs back 

 into the body cavity where it joins the urethra. The seminal vesicles 

 are glandular attachments on the sides of the vasa deferentia which 

 secrete a fluid that is necessary to stimulate the sperms to active move- 



