296 THE PHYSIOLOGY OF REPRODUCTION 



high. Lutein is lieing formed actively in the liver, which is yellow. 

 I'.nt the Intein does not ap]>ear in the hlood, probably l>eeause the 

 saoculina roots absorb it. 



This production in the male crab of a metabolism of the female 

 tv]K> by infection with Sacculina may not stop merely at the appear- 

 ance of female secondary sexual characters in the male, but may go 

 so far that ova are produced in the testes. 



These remarkable facts have led Doucaster 1 to assume that all 

 individuals contain potentially the characters for both sexes are, in 

 fact, potential hermaphrodites. Sex is determined by an additional 

 factor which suppresses the characters of one sex and causes those of 

 the other sex to appear. The sex-determining factor does not 

 introduce the characters of the corresponding sex, but merely 

 releases them. And it does this by determining a certain type of 

 metalxilisni. In other words, metabolism determines sex, not sex 

 metabolism. 



THE MALE GEXEHATIVE ORGANS 

 The 



The M-men, i.e. the fluid discharged by an ejaculation, is the 

 toi-y product of the testis, epididymis, vesiculae seminales, 

 pn "state and Littrd's gland. In man it is a tlvjck, viscous, yellowish, 

 opalescent fluid, which after ejaculation solidifies at first and after- 

 wards Wonies thud again. It has a peculiar smell, which becomes 

 ven more noticeable on heating. Its reaction is alkaline. Its 

 sjH'citic gravity lies between 1'02 and T04. The amount discharged 

 in an ejaculation is given differently by different authors, and 

 Ip-ohablv varies with different individuals, and even with the same 

 individual at different times. From the figures given in the literature 

 "' gm. may be taken to le the average amount. 2 In a normal 

 emission of man Lode calculated that there are about 226 million 

 spermatozoa, and that alnjut 340,000 million must be produced in an 

 individual between the ages of twenty-five and fifty-five. 



The different classes of animals show great differences in the 

 volume of semen ejaculated and in the relative proportion between 

 the sjK-rmato/oa and the liquid part of the semen in which they are 

 susj.ended. 2 The -emeu of different animals also differs in its 



1 iMicaster, "The Physiology of Sex Determination," Hrit,'*!, AMO<:, 1913, 

 . 671. 



e Acton, /'1,,,-r,',,,,.* .,,/ />/,, -,/,.,-.< <>f tl"' H'-j.mdint;,; Organs, 3rd Edition, 

 .ndoii, I^;L'. Lode, " I'ntersuchungen iiber die Zahlen und Regenerations 

 \ erauteMM der Speiinatozoiden bei Hund und Mensch," 1'ftiiger's Arch, vol i 



Mantegazza, ffat. Sfcd. Ita/., Lonibardia, 1866, quoted /i-om Lode. 

 3 Iwan<-tt, ' I.. Spenue de quel<|ue Mammifci-es," Compt. fatul. Soc. de &'ol. t 

 vol. Ixxx., HM7. 



