HVHKIDIS.M AMONG COCKATOOiS. 27 



cliaracter, the evidence, as far as it goes, would point to a 

 real blending of the characters of the parents, and the 

 probable absence of so-called gametic purity, or the segrega- 

 tion of characters in their sexual elements. 



If characters do not blend, and each hybrid parent, what- 

 ever the external appearance may be, produces germ-cells in 

 equal numbers capable of producing either one character or 

 the other, but not a mixture of both, then the relationship 

 found by Mendel and others would naturally follow in the 

 offspring by the law of chance in the fortuitous union of 

 the male and female elements. 



The hybrids of Mendel, De Viies, Bateson, and other 

 observers are more generally crosses of varieties of the 

 same species, and the reason why the crosses between 

 different species have not been more often employed is 

 owing to the fact that these hybrids are frequently sterile 

 among themselves ; but it might be reasonably expected 

 that the appearance of dominant characters would be more 

 often observable in the first generation of hybrids of distinct 

 species, if any approach to gametic purity actually occurred 

 in their sexual cells. 



If differentiation of the sexual cells with regard to alterna- 

 tive characters of the parents really occurs in these hybrids, 

 it is highly remarkable that the parent-hybrid itself should 

 usually be approximately intermediate in all its characters 

 between the two parent-species. The fact indicates that the 

 great majority of the characters are capable of blending. 

 Should the Mendelian relationship possess that universality 

 which some are inclined to attribute to it, the hybrids derived 

 from the crossing of distinct species ought certainly to afford 

 some decisive evidence in its support. 



It is becoming increasingly obvious that MendeFs law in its 

 original sense is of quite limited application, since very many 

 apparently simple characters appear to blend intimately, so 

 that there can be no question of gametic purity or segregation. 



Into the debatable question that the blending is only 

 apparent, owing to the characters being complex ones which 



