THE CYTOLOGICAL PROBLEMS ARISING 

 FROM THE STUDY OF ARTIFICIAL 

 PARTHENOGENESIS 



PART II 



By D. ward-cutler. M.A. (Cantab) 

 Rothamsted Experimental Station, Harpenden 



In a previous paper * certain evidence was given in support of 

 the theory of the individuaUty of the chromosomes, and for 

 the beUef that the X chromosomes are intimately correlated 

 with sex-determination. It is our purpose here to discuss 

 artificial parthenogenesis, and to see what light it throws 

 on these and other cytological conceptions. Taking first the 

 question of sex-production, unfortunately, the number of cases 

 in which it has been determined for parthenogenetically raised 

 animals are at present very few and confined to only one or 

 two species. 



Loeb * reports that out of nine parthenogenetically raised 

 frogs seven were males and one a female. This somewhat 

 unexpected result led him to conduct a second series of ex- 

 periments, in which, as before, every precaution was taken 

 to ensure that the eggs laid had not been fertilised. Partheno- 

 genesis was induced by the puncture method of Bataillon, 

 and, of the eggs so treated, ten developed into frogs, one being 

 a female. There seems no doubt, therefore, that both sexes 

 may develop from parthenogenetic frog eggs. In the sea- 

 urchin Delage has repeatedly tried to rear adults from partheno- 

 genetic eggs, but at present with only one success. In this 

 case the adult animal was a male. 



This exceedingly scanty data is all there is, at the moment, 

 to discuss ; consequently, any conclusion that may be reached 

 can only be regarded as provisional, since the accumulation of 

 more facts, as to the sex of animals so raised, will probably 

 have a modifying or even subversive effect. 



Nevertheless, we know definitely that in the frogs both 



1 Cutler, D. W., Science Progress, No. 59, 1921, p. 435. 



2 Loeb, J., Proc. Nat. Acad. Sci., 4, 1918, p, 60. 



71 



