282 THE PHYSIOLOGY OF REPRODUCTION 



two pigments — a red pigment, Vitellorubin, which is extremely 

 sensitive to light, and a yellow pigment, Vitellolutein. These 

 pigments belong to the lipochromes, which have been men- 

 tioned above. Knikenberg ^ has examined the pigments of a 

 number of other Invertebrates. All. these hpochromes have 

 characteristic absorption spectra. 



The hpochromes of Maja are of special interest, because a 

 similar pigment, Tetronerythrin, has been found in the blood 

 of Maja and other Crustacea. The amount present in the blood 

 shows considerable variation. According to Heim ^ it is com- 

 pletely absent in the blood of the male, and appears in the blood 

 of the female during ovulation. At this period also the ovaries, 

 which usually have a yellowish or whitish colour, become first 

 bright yellow and then red. In Heim's ^ view this hpochrome 

 is not formed in the ovary but in some other organ of the body, 

 and passes at the period of ovulation into the blood, which 

 carries it to the ovaries. 



The same author, together with Abelous,* has proved the 

 existence of some ferments in watery and glycerine extracts of 

 the eggs of various Crustacea. A diastatic, a tryptic, and an 

 inverting ferment were found. They are stated to increase in 

 strength during the maturation of the ovum. 



The Male Generative Organs 



The Semen 



The semen, i.e. the fluid discharged by an ejaculation, is 

 the secretory product of the testis, epididymis, vesiculse 

 seminales, prostate and Littre's glands. In Man it is a thick, 

 viscous, yellowish, opalescent fluid, which after ejaculation 

 solidifies at first and afterwards becomes fluid again. It has a 

 pecuhar smell, which becomes even more noticeable on heating. 



1 Krakenberg, Verghichende physiologische Stvdien : II. Reihe, 3 

 Abteilung, 1882, p. 6. 



2 Helm, "Sur les Pigments des (Eufsdes Crustac^s," Gomptes RendusSoc. 

 Biol, Tol. xliv., 1892, p. 467. 



' Heim, Etudes sur le Sang des Cruataces, Paris, 1892. 

 * Abelous and Heim, " Sur les Ferments des (Eufs des Crustac^s," Gompt. 

 Rend. Soc. Biol., vol. xliii., 1891, p. 273. 



