CHAP, i.] MALE OKGANS. 369 



may largely depend on the condition of the secretions in the 

 vagina and uterus. In this connection it may be noted that the 

 movements of a spermatozoon-like ciliary movements are favoured 

 by fluids having a weak alkaline reaction, whereas almost any 

 degree of acidity (unless used to neutralize excessive alkalinity) 

 arrests them ; and the mucous secretion of the uterus while it is 

 alkaline at the neck of the uterus becomes acid as it passes down 

 the vagina. Hence it might be inferred that those spermatozoa 

 only which rapidly find their way into the os uteri manifest 

 vigorous movements ; but it would be dangerous to lay too great 

 stress on this. 



943. The semen contains a relatively large quantity of solid 

 matter, and this in turn is to a great extent furnished by the 

 spermatozoa ; indeed the spermatozoa form so large a portion of 

 the semen that the chemical substances present in the former are 

 dominant in the latter. The head of a spermatozoon appears to be 

 largely composed of the body or group of bodies known as nuclein 

 or nucleo-albumin, a result which supplies chemical evidence of the 

 nuclear nature of the spermatozoan head ; and nuclein forms a 

 considerable portion of the solid matter of the whole semen. 

 Lecithin is also present in the semen in considerable quantity ; 

 otherwise the chemical features of the secretion, which are as yet 

 imperfectly known, present no special interest. The crystals found 

 in dried semen are not as was once thought of a proteid nature 

 but are compound phosphates containing an organic base. As 

 discharged in coitus the semen proper from the testicle is mixed 

 with the prostatic and other secretions. 



From the testicle itself various forms of proteid of the globulin 

 class have been extracted; and glycogen is not unfrequently 

 present. 



944. The testis is peculiarly rich in lymphatics ; they occur 

 between the tunica vaginalis and tunica albuginea, are abundant in 

 the latter, in the reticulum supporting and in the septa separating 

 the seminal tubules and their continuations, as well as in the 

 connective tissue binding together the coni vasculosi and the 

 coils of the epididymis. It should be added that in many 

 animals masses of polyhedral granular nucleated cells, sometimes 

 assuming the form of occluded tubules, are found intercalated 

 among the proper seminal tubules. They are especially abundant 

 in the testicle of the boar; they appear to take origin from the 

 Wolffian body, but the purpose of their presence is wholly 

 obscure. 



Accessory Organs. 



945. The vas deferens passing from the scrotum through 

 the inguinal ring into the abdomen, finds its way to the under 

 surface of the neck of the bladder, and here, while maintaining 

 the general features of its structure though somewhat dilated, is 



24 



