COVEBIXGS OF THE COED AND TESTIS. 965 



mechanical stimuli, but, apparently, not by electricity. By its action the 

 testes are drawn up or sustained, and at the same time the skin of the 

 scrotum is more or less corrugated. 



3. The intercolumnar or spermatic fascia, a very thin and transparent but 

 relatively firm layer, derived from the tendon of the external oblique muscle 

 of the abdomen, is attached above to the margins of the external ring, and 

 is prolonged downwards upon the cord and testicle. It lies at first beneath 

 the superficial fascia, but lower down beneath the dartos, and it is inti- 

 mately connected with the layer next in order. 



4. The cremasteric layer is composed of scattered bundles of muscular 

 tissue, connected together into a continuous covering by intermediate 

 areolar membrane. The red muscular portion, which is continuous with the 

 lower border of the internal oblique muscle of the abdomen, constitutes the 

 cremaster muscle (p. 251), or tunica erythro'ides, and the entire covering is 

 named the cremasteric fascia. 



5. The infundibuliform fascia, continuous above with the fascia transver- 

 salis arid the subperitoneal areolar membrane, and situated immediately 

 beneath the cremasteric fascia, invests the cord completely, and is connected 

 below with the posterior part of the testicle and the outer surface of its 

 serous tunic. 



On forcing air beneath the infundibuliform fascia, a quantity of loose and 

 delicate areolar tissue is seen to connect its internal or deep surface with the 

 vas deferens and spermatic blood-vessels, and to form lamellsa between them. 

 This areolar tissue is continuous above with the subserous areolar tissue 

 found beneath the peritoneum on the anterior wall of the abdomen ; below, 

 it is lost upon the back of the testicle. Together with the infundibuliform 

 fascia just described, it forms the fascia propria of A. Cooper. 



Lying amongst this loose areolar tissue, in front of the upper end of 

 the cord, there is often seen a fibro-areolar band, which is connected 

 above with the pouch of peritoneum found opposite the upper end of the 

 inguinal canal, and which reaches downwards for a longer or shorter distance 

 along the spermatic cord. Occasionally it may be followed as a fine cord, 

 as far as the upper end of the tunica vaginalis ; sometimes no trace of it 

 whatever can be detected. It is the vestige of a tubular process of the 

 peritoneum, which in the fcetus connects the tunica vaginalis with the 

 general peritoneal membrane. The testicle is placed in the abdomen during 

 the greater part of foetal life ; but at a period considerably prior to its 

 escape from the abdominal cavity, a pouch of peritoneum already extends 

 down into the scrotum. Into this pouch or processus vaginalis peritonei 

 the testicle projects from behind, supported by a duplicature of the serous 

 membrane, named the mesorchium. Sooner or later after the gland has 

 reached the scrotum, the upper part or neck of this pouch becomes 

 contracted and finally obliterated, from the internal abdominal ring down 

 nearly to the testicle, leaving no trace but the indistinct fibrous cord already 

 described, whilst the lower part remains as a closed serous sac, into which 

 the testicle depends, and which is thenceforth named the tunica vaginalis. 



In the female an analogous pouch of peritoneum descends, in the foetus, 

 for a short distance along the round ligament of the uterus, and has 

 received the appellation of the canal of Nuck. Traces of it may almost 

 always be seen in the adult. 



The neck of the processus vaginalis sometimes becomes closed at intervals only, 

 leaving a series of sacculi along the front of the cord ; or a long pouch may continue 

 open at the upper end, leading from the abdominal cavity into the inguinal canal. 



