286 THE PHYSIOLOGY OF REPRODUCTION 



Choline, which gives the same reactions as spermine with 

 iodine and alloxan, has also been stated to occur in the 

 semen. 



The various glands of the genital tract contribute to the 

 formation of the semen in the following way : 



The spermatozoa are formed in the testis, which secretes an 

 albuminous fluid as the medium in which the spermatozoa 

 move about. Crystals smaller than the crystals of spermine- 

 phosphate have been observed by Lubarsch l in the tubules of 

 the testis. They are insoluble in formol and 50 per cent, 

 acetic acid, and swell up under the action of alkali. Other 

 crystalloid rod-like formations in the interstitial cells have been 

 described by Reinke 2 and von Bardeleben. 3 The nature of 

 these crystals, which have been found so far only in human 

 testes, is unknown. Amyloid bodies, which are coloured blue 

 with difficulty by iodine, have been observed by Dares te. 



The secretion of the epididymis has not been chemically 

 investigated. The vesicula) seminales secrete a substance of a 

 protein nature. Both these secretions have a faintly alkaline 

 reaction. 



In the guinea-pig the protein substance secreted by the 

 vesiculae seminales clots if brought in contact with blood. This 

 property is perhaps a means whereby fertilisation is ensured, 

 since in the guinea-pig coitus may take place immediately 

 after the termination of the previous pregnancy, when the 

 uterus is still widely dilated. This unfavourable condition is 

 compensated for by the formation of a clot brought about by 

 the action of the semen on the blood which is still present in 

 the uterus. 4 



The prostate gland secretes an opaque fluid having a faintly 

 acid reaction (which may become neutral or alkaline in in- 



1 Lubarsch, " tiber das Vorkommen Krystallinischer und Krystalloider 

 Bildungen in den Zellen des Menschlichen Hodens," Virchow's Archiv, 

 vol. cxlv., 1896. 



2 Reinke, " Beitrage zur Histologie des Menschen," Archiv f. mikroskop. 

 Anatomic, vol. xlvii., 1896. 



3 Bardeleben, " Beitrage zur Histologie des Hodens und zur Sperrnato- 

 genese beim Menschen," Archiv f. Anatomie u. Physiologic, Anatomische 

 Abteilung, Supplement, 1897. 



4 Landwehr, "fiber den Eiweisskorper der vesicula seminalis der Meer- 

 schweinchen," Pfluger's Archiv, vol. xxiii., 1880. 



