SIZE INHERITANCE IN DUCKS 
JOHN C. PHILLIPS 
From the Laboratory of Genetics of the Bussey Institution. 
The inheritance of size in animals is a question of great theo- 
retical interest, but difficult to analyze. 
Lock (’06) in the case of maize showed that height of the plant 
is not inherited as a simple Mendelian character. Castle (’09) 
showed the same to be true of the weight and of various skeletal 
dimensions of rabbits, and characterized such inheritance as 
blending. 
Ghigi (09) referring to a cross which he made between Paduan 
fowls and bantams stated that in size of body and of eggs produced 
the (F,) cross-bred individuals were intermediate between the 
parent races, and that later generations showed no tendency to 
return to the conditions found in the parent races. The number 
of animals studied by Ghigi was small and no great stress was 
laid upon the point of non-segregation. 
Emerson (710), however, after a more detailed and exact study 
of the inheritance of height in maize, and of several other size and 
shape characters in gourds, found that while F2 was strictly inter- 
mediate between the parents and no more variable, F, showed a 
greatly increased variability, which he interpreted as ‘‘merely 
a mathematical way of expressing the fact that the F, individuals 
exhibit marked segregation of size and shape characters.’”’ Such 
an interpretation was made possible by the discovery by Nillson- 
Ehle (09) and by East (10) that a Mendelizing character may 
have multiple germinal representation, in which case, though 
physiologically a single unit-character, it may produce dihybrid, 
trihybrid, or even more complex Mendelian inheritance ratios 
1 Contribution No. 12. 
369 
