780 GENERATION AND DEVELOPMENT. 



them are developed ; and in either case the organ soon 

 begins to assume a relatively lower position in the body ; 

 the ovaries being ultimately placed in the pelvis ; while 

 towards the end of foetal existence the testicles descend 

 into the scrotum, the testicle entering the internal 

 inguinal ring in the seventh month of foetal life, and com- 

 pleting its descent through the inguinal canal and external 

 ring into the scrotum by the end of the eighth month. A 

 pouch of peritoneum, the processus vaginalis, precedes 

 it in its descent, and ultimately forms the tunica vaginalis 

 or serous covering of the organ ; the communication 

 between the tunica vaginalis and the cavity of the perito- 

 neum being closed only a short time before birth. In its 

 descent, the testicle or ovary of course retains the blood- 

 vessels, nerves, and lymphatics, which were supplied to it 

 while in the lumbar region, and which are compelled to 

 follow it, so to speak, as it assumes a lower position in the 

 body. Hence the explanation of the otherwise strange fact 

 of the origin of these parts at so considerable a distance 

 from the organ to which they are distributed. 



The means by which the descent of the testicles into the 

 scrotum is effected are not fully and exactly known. It 

 was formerly believed that a membranous and partly 

 muscular cord, called the gulernaculum testis, which extends 

 while the testicle is yet high in the abdomen, from its 

 lower part, through the abdominal wall (in the situation 

 of the inguinal canal) to the front of the pubes and 

 lower part of the scrotum, was the agent by the contraction 

 of which the descent was effected. It is now generally 

 believed, however, that such is not the case ; and that the 

 descent of the testicle and ovary is rather the result of a 

 general process of development in these and neighbouring 

 parts, the tendency of which is to produce this change 

 in the relative position of these organs. In other words, 

 the descent is not the result of a mere mechanical 

 action, by which the organ is dragged down to a lower 



