392 IIYOLOGY. 



<ti<r. 224 A). This gradually penetrates the abdominal wall and 



i > into a fold of the >kin, which is developed in the pubic region, 



M> will be shown in a subsequent section (see tig. 231 gw). The 



opening of tin- hernia-like evagination, which leads into the body- 



cavity. i> called the him'i' ht</uinal [abdominal] ring (Ir) ; the portion 



which tra\er> > t he musculature of the abdominal wall, the inguinal 



: ;ind tin- blind <-nd which is expanded within the dermal fold, 



the scrotum. 



In its migration the testis (fig. 224 B) also sinks down into this 

 peritoneal fold, whereby it remains undetermined whether HUNTER'S 

 ligament exercises an influence on it or not. The entrance into the 

 inguinal canal usually takes place in the eighth month, into the 

 M-rotum in the ninth month, so that at the end of embryonic life 

 the descent is, as a rule, completed. The canal then closes by 

 fusion of its walls, and thereby the testis comes to lie in a sac 

 constricted off from the abdominal cavity and enclosed on all 



sides. 



The various enveloping structures of the testis also become intelli- 

 gible from the sketch of the development just given. Since tin- 

 cavity which shelters it is simply a detached portion of the body- 

 cavity, it is, as a matter of course, lined by peritoneum (fig. 224 4 '). 

 This is the so-called tunica vaginalis propria, on which, as on other 

 regions of the peritoneum, we have to distinguish a parietal lay. i 

 ( 4 ') lining the wall of the sac and a visceral layer ( 4 ") investing the 

 testis. Outside of this follows the tunica vaginalis communis ( 3 ') ; 

 it is the evaginated, and at the same time extraordinarily attenu- 

 ated, layer of muscles and fasciae ( 3 ) of the abdominal wall. Con- 

 sequently it also contains some muscle-fibres enclosed in it, which 

 are derived from the musculus obliquus abdominis internus, and 

 i itute the suspensory muscle of the testis or cremaster. 



In the descensus testiculorum, which should normally be com- 

 pleted in Man at the end of embryonic life, interruptions may, under 

 certain circumstances, occur and produce an abnormal location of the 

 te>tis. which is known under the name of cryptorchism. The do- 

 remains incomplete. Then the testes of the recently born child 

 ither found to be located in the body-cavity, or they still stick ta>t 

 in the wall of the abdomen, in the inguinal canal. In consequence 

 lotum feels small, flabby, and flaccid. 



Such anomalies are designated as iiiliii>ifin matybrmationti l>e<.-au>e 

 they are explained by the fact that the processes of development 

 not reached their normal termination. 



