RESULTS OF CROSSIXi, TWO IIEMIPTEROl - SPECIES. 



It would see-in I hat a cross between two species of these Hcmip- 

 tera, one of which contains an exclusively male character which 

 is absent in the other, should furnish some trustworthy evidence 

 for or against the hypothesis that the factors for determining 

 sex are located in a definite chromosome of the so-called male 

 and female-producing spermatozoa. 



\Ye believe that our results from this experimental work are 

 in harmony with our cytological evidence on this point and 

 that these results support the skepticism of those investigators 

 who believe that the evidence given by the chromosomes does 

 not warrant the assumptions that have endowed these cell 

 structures with causal attributes. 



XEW YORK, 



December, 1912. 



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 Castle, E. W. 



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