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ANATOMY AND PHYSIOLOGY OF 



formed in a situation remote from that in 

 which they are destined to carry on their 

 functions; "the colt has no testicles," is 

 the common observation of the unim- 

 formed on these matters ; and we know 

 ourselves that the purse is without them, 

 bn.t we know, in addition, that they exist 

 ready-formed within the abdomen, and that 

 they will descend at a certain period of age 

 into the proper receptacle, the scrotum. 

 During the foetal state we jfind the testicles 

 more or less developed, tinged with a blush 

 of red, lodged beneath the psoas muscles, 

 in contact with the inferior borders of the 

 kidneys, covered and retained in their situ- 

 ations by peritoneum, and concealed by the 

 intestines around them. Here they receive 

 their arteries from the contiguous trunk — 

 the posterior aorta ; the vasa deferentia 

 run forward to them, and the cremosters 

 likewise turn forward instead of backward ; 

 there being at this time no such thing as a 

 spermatic cord. Thus placed, the testicle 

 may be regarded as one of the glands of 

 the abdomen ; indeed it has considerable 

 similarity to the kidney — receiving its ves- 

 sels from the same contiguous source, and 

 sending a long duct backward into the 

 cavity of the pelvis ; nor does there appear 

 any conclusive reason W'hy it should not 

 perform the same office in that situation 

 that it does in the scrotum, and particu- 

 larly since it is known that in birds the tes- 

 ticles remain within the abdomen during 

 life. From the part where the blood ves- 

 sels enter, we find growing a whitish sub- 

 stance, extending backward, diminishing 

 in breadth as it recedes, passing through 

 the ring where the filus of the cremoster 

 may be traced upon it, and whence it is 

 prolonged into the scrotum, growing nar- 

 row^er and narrower until it vanishes ; this 

 substance, regarded by some simply as a 

 ligament, was considered by ]\Ir. Hunter 

 as the gubernaculum or pilot, by means of 

 which the testicle is directed in its passage 

 from the abdomen into the scrotum. Quit- 

 ting the spot where it has been formed and 

 matured, the testicle gradually retrocedes, 

 guided by the gubernaculum, until it ar- 



rives on the internal ring, which, at this 

 time (like every other part of the parietes) 

 is closed by peritoneum ; this temporary 

 obstruction it overcomes by drawing the 

 membrane down along with it through the 

 ring, and carrying the pouch made thereby 

 down into the scrotum ; the gubernaculum 

 at the time undergoing a complete in- 

 version. This accounts for the production 

 of the tunica vaginalis, and explains how 

 that membrane comes to be doubled or re- 

 flected; the testicle, receiving originally (as 

 an abdominal viscus) one close adherent 

 peritoneal tunic, and acquiring another 

 which forms a loose covering as it passes 

 through the ring, must necessarily have 

 two ; 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 membrane, though 

 everywhere in contact, are prevented from 

 adhering together by a continual exhala- 

 tion of the natm-al 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 unacquainted wdth 

 the immediate cause of their descent, so 

 we are unable to give any rational explana- 

 tion of this phenomenon. I have under- 

 stood, that in many of these cases the 

 glands have been found to be but imper- 

 fectly developed : this, however, is not with- 

 out exception. 



Period of Descent. — Most animals have 

 their testicles wdthin 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 they arrive in the scrotum. 

 In the horse, they pass through the ring 

 about the sixth or seventh month before 



