THE MENDELIAN CLUE 235 



character. If this be so, and if fertilization be 

 fortuitous, then the Mendelian proportions must be 

 exhibited by the offspring of the hybrid generation, 

 namely, 25 per cent,, pure recessives, 25 per cent, 

 pure dominants, and 50 per cent, impure dominants 

 (like the original hybrids), which, if inbred, will 

 have offspring in the same 1:2:1 proportion as 

 regards the particular unit character observed. 



It is often asked whether there are not, as used 

 to be believed without question, other modes of 

 inheritance besides this Mendelian mode, and this 

 continues to be the subject of investigation. Does 

 the mulatto exhibit as regards skin-color a 

 blend of the characters of his parents, or is the 

 matter less simple than it seems? Are not the 

 hybrids between long-eared and short-eared rabbits 

 very exact intermediates between their parents, and 

 do not hybrid cockatoos show diagrammatic blend- 

 ing? Or are such cases sufficiently interpreted on 

 Mendelian lines as due to incomplete dominance, or 

 to the fact that one character may have multiple 

 factors which do not get cleanly segregated in the 

 history of the germ-cells. It is one of the merits of 

 Professor James Wilson's recent introduction to 

 Mendelism * in its practical aspects that it shows how 

 results which do not seem consistent with Mendelian 

 theory may nevertheless be brought into conformity 

 with it. Disturbances in the Mendelian distribu- 

 tion may be due to factors cancelling one another, 

 jostling one another, coupling with one another, 

 1 A Manual of Mendelism, 1916. A. & C. Black. 



