The human epididymis is currently considered merely an outlet duct for spermatozoa, though why a sperm one five-hundredth inch long must float 20 feet—the length of the small intestine and more than a hundred thousand times its own length—before arriving anywhere is not thus explained. It is known that in quadrupeds the epididymis possesses two functions which may explain its extraordinary length: First, it is a reservoir for sperms, for no quadruped possesses hollow seminal vesicles connected with the vasa deferentia as reservoirs, as does man. Most of them, except the carnivora, are provided with organs called seminal vesicles, but these are usually racemose glands like Cowper's glands; moreover, their ducts empty into the utricle or directly into the urethra, without having any connection with the vasa deferentia (fig. 1). In man, the vas deferens empties obliquely into the seminal vesicle, as does the ureter into the bladder—an arrangement not