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THE AM ERIC AX XA TV EALlsT 



[Vol. XLV 



species, set apart by mere differences of sex and minor 

 traits, the basal protoplasmic stereometry and the funda- 

 mental proteid constitution must be in large measure 

 identical, so that bi-parental inheritance, if extending to 

 all the details it lias been assumed to embrace, would be 

 largely a matter of duplicating identical protoplasmic 

 constituents. It is an obvious fact, however, that the 

 egg contributes vastly more cytoplasm than the sper- 

 matozoon, and in consequence the developing organism 

 is more maternal than paternal in origin. I have argued 

 this point at some length in a former paper, 10 where I at- 

 tempted to show that we are not justified in asserting 

 that the entire quota of characters which go to make up a 

 complete living organism are inherited from each parent 

 equally, but that rather we must restrict our assertion of 

 equal inheritance to the sexual and specific differences 

 which top off, as it were, the more fundamental organ- 

 ismal features. I further pointed out that since the actual 

 manifest physical things contributed equally by each 

 parent were the chromosomes, we might legitimately look 

 to them as the chief source of the factors which determine 

 individual differences. We know that a single reduced or 

 haploid set of chromosomes is sufficient for normal de- 

 velopment, both from the fact of artificial parthenogene- 

 sis, and the fertilization of non-nucleated egg fragments ; 

 hence the egg must contain all the possibilities of a new 

 organism. But the only measurable things contributed 

 by the sperm-cell are the individual characters of the 

 male line. 



We may infer then that the chromosomes of both male 

 and female origin work together on or with the other 

 germinal contents of the fertilized egg, and these are pre- 



