72 Ooariotomy and Sex 



removed tbe remaining (left) ovary contained at least seven corpora 

 lutea, and the remaining (right) ovary of the second rat contained at 

 least eight. These corpora lutea were all of similar age in each animal, 

 and clearly distinguishable from the older luteal tissue present in the 

 ovaries. 



These facts seem to us to indicate without any doubt that in the rat 

 it is not true that ova determining one sex are produced from one 

 ovary, and those determining the opposite sex from the other, for each 

 rat, with one ovary completely removed, produced young of both sexes. 

 This does not of course prove that the "right and left ovary hypothesis" 

 is not true for man, but its definite disproof for another mammal detracts 

 from its probability. It should be pointed out however that the 

 evidence for alternate male and female ovulations in man, collected by 

 Dr Rumley Dawson and others, is not in any way affected. In our 

 opinion the weakest part of his evidence is that dealing with the pro- 

 duction of ova determining different sexes by the two ovaries, and it is 

 not impossible that this hypothesis may be false, and yet that in 

 general alternate ovulations may be of different sex, so making sex- 

 prediction possible. It is very desirable that those who have extensive 

 opportunities of testing this hypothesis — which involves knowing not 

 only the date of birth and whether the child is " full time " in each 

 case, but also whether the menstrual periods are normal and regular — 

 should have the matter in mind and keep records whenever possible. 



[^Note. The operations described were performed by F. H. A. 

 Marshal] ; the disisections by L. Doncaster.] 



K 



