478 
The Ohio Naturalist. 
[Vol. XV, No. 6, 
the expected Mendelian ratio when two factors were required to 
produce the brown color. When he crossed a red and white¬ 
grained wheat, the F-2 generation segregated into the ratio of 63 
red to 1 white grain. From this Nilsson-Ehle reasoned that three 
independent factors were required to produce the red color. 
Although the operation of Mendel’s law of heredity with 
respect to qualitative characters has been amply proven, there is 
a considerable doubt in the minds of many foremost geneticists as 
to whether or not quantitative characters are inherited in a 
Mendelian fashion. It has only been within the last few years 
that students of heredity have turned their attention to the prob¬ 
lem of inheritance of quantitative characters. 
The first man who worked definitely with quantitative char¬ 
acters seems to have been Lock in 1906 (36) who crossed a tall 
race of maize with a shorter race and obtained an F-l hybrid 
intermediate in size between the parents. The F-2 plants showed 
no segregation when crossed with one of the parents. Lock 
showed that the height of a plant is not inherited in a simple 
Mendelian fashion. 
Castle in 1909 (8) worked with the ear-lengths of rabbits and 
discovered what he called “blending inheritance”. In summing 
up his own work Castle says, “A cross between rabbits differing 
in ear-lengths produces an off-spring with ears of intermediate 
length, varying about the mean of the parental ear-lengths. 
* * * * A study * * * * shows the blend of parental 
characters to be permanent. No reappearance of the grand- 
parental ear-lengths occurs in the F-2 generation, nor are the 
individuals of the second generation as a rule more variable than 
those of the first generation of cross-breeds. * * * * The 
linear dimensions of the skeletal parts of an individual approx¬ 
imate closely the mid-parental dimensions”. 
Ghigi in 1909 (22) crossed a Paduan fowl and a bantam and 
found that the size of body and eggs of the F-l cross-bred individ¬ 
uals were intermediate between the parent races. Only a limited 
number of the later generations were grown and these showed no 
segregation of size characters. 
Mendelians have not recognized the validity of any so-called 
“blending inheritance” except that which Castle has shown. 
And these results on the ear-lengths of rabbits have been explained 
according to the Mendelian notation by Lang, whose explanation 
is recognized as possible by Castle. Some Mendelians object to 
this “blendmg inheritance” on the grounds that the number of 
individuals grown was not large enough to prove that segregation 
does not occur in the F-2 generation and Castle has admitted the 
possibility of this fact. 
