610 GENERATION AND DEVELOPMENT. 



compelled to follow it, so to speak, as it assumes a lower posi- 

 tion 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 gubernaculum 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 neighboring 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 position, 

 but rather one change out of many which attend the gradual 

 development and rearrangement of these organs. It may be 

 repeated, however, that the details of the process by which the 

 descent of the testicle into the scrotum is effected are not 

 accurately known. 



The homologue, in the female, of the gubernaculum testis, 

 is a structure called the round ligament of the uterus, which ex- 

 tends through the inguinal canal, from the outer and upper 

 part of the uterus to the subcutaneous tissue in front of the 

 symphysis pubis. 



At a very early stage of fostal life, the efferent ducts of the 

 Wolffian bodies of the kidneys and of the ovaries or testes, 

 open into a receptacle formed by the lower end of the allan- 

 tois, or rudimentary bladder ; and as this communicates with 

 the lower extremity of the intestine, there is for the time, a 

 common receptacle or cloaca for all these parts, which opens to 

 the exterior of the body through a part corresponding with 

 the future anus. In a short time, however, the intestinal por- 

 tion of the cloaca is cut off from that which belongs to the 

 urinary and generative organs ; a separate passage or canal to 

 the exterior of the body, belonging to these parts, being called 

 the sinus urogenitalis. Subsequently, this canal is divided, by 

 a process of division extending from before backwards or from 

 above downwards, into a " pars urinaria" and a " pars genita- 

 lis." The former, continuous with the urachus (p. 587), is 

 converted into the urinary bladder. 



The Fallopian tubes, the uterus, and the vagina are de- 



