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