DISCOVERY 



239 



porated with the rest of the chromosomes. As a 

 •consequence, one of the resulting- cells still has the 

 proper complement of two X's, while the other has 

 but one. The part with two X's becomes female ; that 

 with one, male. If the two X's were carrying- 



Fig. 2.— GYNANDROMORPHS OR SEX-MOSAICS. 

 (a) Pine moth {Bupalus pinaritis) ; female on left, male on right. 

 ■(6) Ant {MyrmicH scahrinodts) ; male on left, worker (sterile female) on right. 

 Reproduced from " The DeterminaUon of Sex," by Prof. L. Doncaster, F.R.S., 

 ■by permission of the Editors of the "Journal of Genetics" and of the 

 Cambridge University Press, 



different sex-linked factors, sex-linked characters also 

 could be different in the two regions of the body. In 

 mammals, these sex-mosaics, as we may call them, 

 do not occur, because the substances secreted bv the 

 reproductive org-ans pass into the circulation, and 

 influence the sexual characters equally all over the 

 body. 



.■^n even more remarkable abnormality is provided 

 by what are called intersexes. The gipsy moth, that 

 terrible forest plague, has a well-marked varietv in 

 Japan. When this is crossed with the European race, 

 verv curious results are obtained. When a Japanese 

 male is crossed with a European female, 50 per cent, 

 of the offspring are normal males, but the remainder 

 are intermediate between male and female — so-called 

 intersexes. \\'hen these are carefully examined, it is 

 seen (by an examination of their hard parts, -which, 

 once formed, cannot be remoulded) that thev have 

 started their development as females, but ended it as 

 males. They are females which suddenly, during their 

 growth, have by some invisible but inexorable power 

 been switched over to become of the opposite sex. .All 

 degrees of inter.sexuality are known, according to 

 the races employed in the cross. The females may 

 show only the faintest traces of maleness ; may be 

 equally male and female ; may be preponderatingly 

 male ; or finally, in certain crosses, the change of sex 

 may come so early that no trace of female characters 

 appears, and the cross results in males alone. (.See 

 Fig-- 3-) 



Even though half of these all-male broods ought by 

 rights to be females, yet all behave like normal males, 

 and can mate and produce offspring. \\'ith these 

 experiments, carried out over a long series of vears 

 by Professor Goldschmidt, of Berlin, we can at last 

 be sure that it is possible for a complete and func- 

 tional reversal of sex to take place. 



When the cross is made the other wa\-, with a 

 Japanese female and a European male, the first 

 generation is altogether normal. But in the second 

 generation abnormal individuals again appear. This 

 time, however, they are different from those first 

 seen, and on analysis turn out to be intersexual 

 males — i.e., animals which have started as males and 

 been forced to finish their development as females. 



What is the explanation of these strange facts? 

 It appears to lie, ultimately, in the different climates 

 to which the different races are adapted. The 

 Japanese races are adapted to grow more rapidlv. 



Fig. 3.— GIPSV moth {Lvmantria dispar) ; SERIES OF INTERSEXU.^L 

 FEMALES. 



.\bove. slight intersexuality ; below, almost complete transformation to 

 maleness. 



Br permission of the Editor of the "Journal of the Royal Society of Arts.'* 

 {.ifter Goldschmidt.) 



The factor which produces maleness must lie in the 

 sex (X) chromosome, which in moths is double in 

 males, single in females. The factor producing 

 femaleness we cannot yet locate so definitely ; but it 

 has been shown to be transmitted always and only 

 through the mother; let us call it Q. Then all the 



