290 GENERATIVE SYSTEM. 



through the ring, must necessarily have tivo ; and since both are 

 derived from one and the same membrane, it follows that one 

 must be a continuation of the other. These elongations of mem- 

 brane, though every where in contact, are prevented from ad- 

 hering together by a continual exhalation of the natural serous 

 secretion. Any interval that might subsist between them, in 

 course, communicates with the cavity of the abdomen, through 

 the ring, a part that remains open through life: this, however, is 

 not the case with man — in his body the communication is cut off, 

 after the testicles have descended, by a natural contraction and 

 obliteration both of the ring and the inguinal passage. In many 

 instances, one, in some few, both of the testicles, are known to 

 have remained within the belly through life. As we are unac- 

 quainted with the immediate cause of their descent, so we are 

 unable to give any rational explanation of this phenomenon. 

 I have understood, that in many of these cases the glands 

 have been found to be but imperfectly developed : this, however, 

 is not without exception. 



Period of Descent. — Most animals have their testicles within 

 the scrotum at the period of birth. In the human foetus they 

 begin to move about the seventh month ; about the eighth they 

 reach the groins; and before birth arrive in the scrotum. In the 

 horse, they pass through the ring about the sixth or seventh 

 month before birth, and are found within the scrotum at the 

 period of parturition. In some cases, one testicle will not make 

 its appearance for some time after the other ; and as the opera- 

 tion for castration is seldom long delayed, this will account for 

 the rigs (as horses having but one testicle are called) with which 

 we meet every now and then. Again, instances are not wanting 

 in which one testicle has descended to the ring and there remained 

 through life*. 



* In a communication I have been favoured with from Mr. Brettargh 

 (which I have inserted in the second volume of The Veterinarian), is 

 contained the following information on this subject : — " Colts are foaled 

 with their testicles in the scrotum, which remain' there (in ordinary cases) 

 until the fifth or sixth month, \vhen they are taken up between the internal 

 and external abdominal rings, and there remain until the eleventh, twelfth, 

 or thirteenth month, all depending upon the degree of keep, as in some 

 that are well fed the testicles can at all times be found in the scrotum. 

 Were the testicles drawn up into the abdomen, they would be too large to 

 pass through the internal abdominal ring at the time they are wanted to 

 prepare for secretion ; which is occasionally the case, and at once accounts 

 for our meeting with horses that are said to have but one stone. I have 

 seen one instance where both were wanting in the scrotum at four years 

 old." 



