2i A NORMAL HISTOLOGY. 



which represent the remains of foetal organs. Such structures are 

 the paradidymis and the stalked and sessile hydatids. 



The paradidymis, or the organ of Giraldes, consists of irregular 

 tubules lying among the convolutions of the epididymis, which are 

 the atrophic remains of the tubes of the Wolffian body. They 

 are lined with low columnar or cuboidal epithelial cells, often ciliated, 

 and are surrounded by an envelope of vascular connective tissue. 

 The tubules of the paradidymis are usually closed, and frequently 

 contain small quantities of albuminous fluid. 



The pedunculated or stalked hydatid, common to both sexes, 

 probably represents a part of the atrophied duct of the pronephros, 

 the anterior segment of the Wolffian body. The sessile or un- 

 stalked hydatid, on the contrary, is limited to the male subject, 

 and is the slightly expanded proximal end of the rudimentary Mul- 

 lerian duct. These sacs are lined generally by cuboidal cells, and 

 often contain a clear fluid. 



The blood-vessels of the testicle, branches of the spermatic 

 artery, are distributed to the mediastinum and to the loose inner 

 layer the tunica vasculosa of the albuginea, including its pro- 

 longations, the septa. From the vessels coursing within these robust 

 fibrous structures smaller twigs enter the connective tissue and pass 

 between the individual tubules, around which they form rich inter- 

 tubular capillary net- works. The corresponding veins accom- 

 pany the arteries. 



The lymphatics form a superficial capsular net-work, consisting 

 of vessels situated within the tunica albuginea, and a deeper inter- 

 tubular plexus, the radicles of which closely surround the semi- 

 niferous canals. The superficial and the deep lymphatics anastomose 

 to form within the mediastinum larger vessels, which, uniting with 

 those of the epididymis, constitute one of the elements of the 

 spermatic cord. 



Regarding the distribution of the nerves little is definitely known 

 further than the penetration of bundles of mixed fibres between the 

 seminiferous tubules, around which they form plexuses ; the ultimate 

 termination of the end-fibres is unknown. 



THE SEMEN. 



The semen as ejected consists of the secretion of the testicle 

 diluted with that of the seminal vesicles and of the prostate gland, 

 together with the fluid derived from Cowper's glands and the mucous 

 membranes traversed. The secretion proper of the male sexual 

 gland consists almost entirely of spermatozoa ; these latter show no 

 movement when in the concentrated fluid of the testicle or epididy- 

 mis : only after the dilution normally effected by the admixture of 



