STRUCTURE OF VESICUL^ SEMINALES. 293 



cord is richly supplied with thin- walled lymphatics ; these 

 form distinct plexuses in the vascular and nervous layers, whilst 

 a few may be distinguished in close proximity to the muscular 

 tunic of the vas deferens. 



Besides the above-mentioned structures, the body known 

 under the names of Parepididymis, or the organ of Giraldes, 

 composed of tubes, is found at the commencement of the 

 spermatic cord. The tubes are lined by columnar epithelium, 

 differing in no respect from that of the vas deferens. The 

 subjacent mucous membrane is looser and much folded, the 

 folds in some parts resembling glandular depressions. It is 

 composed of connective tissue and elastic fibres united into a 

 plexus, and of numerous small circularly arranged fasciculi of 

 smooth muscular fibres. 



The mucous membrane is surrounded externally by a 

 moderately close venous plexus. 



The vas deferens is present in all Mammals, Birds, scaly Reptiles, 

 and Selachii, and invariably possesses distinctly muscular walls. 

 According to Leydig, the vas deferens of Mammals exhibits numerous 

 glands in its lowest dilated portion, the ampulla, whilst that of Birds, 

 Saurians, and Serpents is destitute of glands. The depressions of 

 the mucous membrane, similar to those already described in Man, 

 were doubtless regarded as glands in the above-mentioned animals. 

 The duct common to the urine and semen in Batrachians contains 

 also smooth muscular fibres in its lowest part (Leydig). 



II. VESICUL^E SEMINALES. In the vesiculse seminales the 

 same parts are found with a few modifications that have just 

 been seen- to be present in the vas deferens. The mucous 

 membrane forms numerous folds of unequal height, that have 

 not always a longitudinal disposition, but in some parts form 

 transverse ridges, and thus the depressions are produced that 

 were considered by Henle to be glands ; the epithelium, like 

 that of the vas deferens, is columnar, and the individual conical 

 or columnar cells are provided with a well-marked basal border 

 of rods that, especially in newly born children, closely resemble 

 short fine cilia. 



The thickness of the mucous membrane amounts to 04 of a 



