24 
Research Bulletin No. 2 
Let us now consider the experimental evidence that is thought 
to show segregation and recombination of factors of the kind that 
have just been discussed. 
Xilsson-Ehle in 1908 stated that he had found greater varia- 
bility in F 2 than in F 1 in numerous crosses where the parents 
differed in quantitative characters. Data were presented, how- 
ever, only on qualitative characters. 
East (1910), in his independent proposal of this method of 
interpreting the inheritance of quantitative characters by a 
Mendelian notation, showed how certain data on the inheritance 
of different numbers of rows of seeds on the ear of maize could 
be thus analyzed. His observations were not sufficiently numer- 
ous, however, to be convincing. 
A little later Emerson's (1910) paper on inheritance of 
quantitative characters appeared. Here segregation and re- 
combination of size factors was clearly shown in three species; 
viz, Cucurbita pepo. Phaseolus vulgaris, and Zea mays. 
Cucurbita pepo. A cross between a long, narrow Crookneck 
squash and a round flat Scallop squash gave an F 1 generation 
intermediate in all respects and an F 2 generation showing a com 
plete series of sizes and shapes running from that of the Crook- 
neck to that of the Scallop. The Means and Coefficients of 
variation were as shown below. The Probable Errors were not 
calculated but the number of individuals was large enough for 
one to have considerable confidence in the results. 
Race or hybrid 
Means 
Coefficients of variation 
Length 
Diameter 
Length 
Diameter 
Cm. 
Cm. 
Per cent 
Per cent 
Crookneck . . 
39.6 
11.4 
17.0 
12.0 
Scallop 
7.4 
17.8 
15 8 
12.6 
Ft hybrid 
17.5 
17.5 
19.0 
12.6 
F 2 hybrid 
19.6 
13.2 
42.7 
58.8 
A cross between a long narrow Spoon gourd and a shorter, 
much thicker Horned gourd gave a similar increase of variability 
in F 2 over that shown by F v 
Race or hybrid 
Means 
Coefficients of variation 
Length 
Diameter 
Length Diameter 
Cm. 
Cm. 
Per cent Per cent 
Horned 
10.3 
9.0 
9.4 9.9 
Spoon 
14.0 
4.2 
15.6 16.0 
12.9 
5.6 
15.8 15.7 
F 2 hybrid 
15.7 
5.5 
37.5 21.2 
