230 SPECIAL HISTOLOGY. 



portion, consists of dense connective tissue containing elongated 

 nuclei. The tunica vaginalis communis, is a dense, tolerably 

 thick membrane, consisting, on the testis, of firm connective 

 tissue, and higher up, of a more lax reticulated tissue with 

 elastic fibres ; it closely surrounds the tunica vaginalis propria, 

 and also invests the spermatic cord, and the lower end of the 

 epididymis. Between it, the tunica propria, and the epididymis, 

 and firmly connected with both tissues, is placed a layer of 

 smooth muscles usually corresponding to the two lower thirds 

 of the testis, — the internal muscular tunic of the testis ; whilst 

 on its outer side is inserted the cremaster, composed of trans- 

 versely striated fibres. The scrotum, lastly, is formed by the ex- 

 ternal muscular tunic of the testis, which is more laxly con- 

 nected with the t. v. communis, — the tunica dartos; with respect 

 to which vid. § 34 ; and by the external integument, which is 

 characterised by its thinness, the absence of fat, the colour of 

 its epidermis, and its, mostly, large sebaceous and sweat-glands. 

 The blood-vessels of the testis and epididymis are derived 

 from the long and slender a. spermatica interna, which, running 

 in the spermatic cord, proceeds from its posterior aspect to the 

 testis, and sometimes entering at once, the corpus High- 

 morianum, sometimes divided into numerous branches, ramifies 

 in the fibrous tunic of the testis and on its inner surface, pro- 

 ceeding towards the anterior border of the gland. The coarser 

 ramification in the parenchyma of the testis proceeds partly 

 from the corpus Highmorianum, partly from the points of origin 

 of the septula testis from the tunica albuginea, into the septula, 

 from which, again, numerous more minute vessels penetrate 

 into the interior of the lobules, constituting a rather wide- 

 meshed plexus of capillaries, 0*003 — 0*008"' in diameter, 

 around the tubuli seminiferi. In the epididymis there is a 

 similar though less abundant plexus, in the formation of which 

 the artery of the vas deferens also participates (fig. 257), whilst 

 the scrotum and the t. vaginalis are richly supplied with vessels 

 from the aa. scrotales and spermatica externa. The veins 

 accompany the arteries, and with respect to the lymphatics, not 

 only are those of the scrotum and vaginal tunics extremely 

 numerous, but, according to the beautiful researches of Panizza 

 (' Osservazioni/ Tab. VIII), confirmed by Arnold, those of the 

 testis are also very much developed. They proceed partly 

 from the interior, partly from the surface of the testis and 



