26 
Research Bulletin No. 2 
two varieties Common Flax and Egyptian flax and its reciprocal 
gave a variable progeny, tho here, too, an intermediate character 
was manifested. Further, the F 2 was but little more variable 
than the F x . Altho this result might easily be explained by 
gametic impurity of the parents, it was so interesting that the 
progeny of extreme individuals was followed to the F 3 generation. 
There was no doubt, from the data obtained in this generation, 
that various F 2 plants did have different gametic formulae, for 
the progeny produced were different. A somewhat similar result 
was obtained when Egyptian flax was crossed with TAnum 
crepitans. 
Length and breadth of petals was studied in a cross between 
Egyptian flax and Linum angustifolium and its reciprocal. In 
both cases the variability of F 2 was greater than that of F 5 . 
In Nilsson-Ehle's extended monograph of 1909, it was stated 
that crosses of wheats and of oats were in progress in which such 
characters as number of seeds per head, hairiness, height, length 
of glume, length of spike, size of seed, hardiness, and resistance to 
rust were being studied. In 1911 that portion of his results 
relating to the internodal length of wheat spikes and resistance 
to rust was reported. Some of the various crosses had been 
followed to the F 3 generation. The data show clearly that 
varietal differences in these characters depend on several inde- 
pendent gametic factors, altho their exact behavior is not known. 
Possibly complete analysis of such a thing as resistance to a 
fungal parasite cannot be cleared up by field work, as Nilsson 
Ehle believes, for there is evidence that genotypic differences in 
the parasites exist which complicate matters. 
Hayes' (1912) paper on tobacco has already been mentioned 
in another connection. He presented data upon number of leaves 
per plant, height of plant, and size of leaf. In each case there 
was a greater variability in F 2 than in F i5 and this difference he 
shows clearly can be most logically described by assuming segre- 
gation and recombination of "size" factors. 
Von Tschermak (1902) some years ago found that an early 
blossoming pea crossed with a late blossoming variety gave an 
intermediate F x and a variable F 2 . Afterwards he found (1904) 
that only a portion of the "early 7 ' and "late" segregates bred true, 
and that this behavior could not be expressed by a simple 
Mendelian formula. In a recent paper (1912) he gives a full 
analysis of his later results on this character complex, and ex- 
presses them with the Mendelian notation by assuming multiple 
factors. 
Belling (1912) has reported a study of a cross between two 
bean varieties that differed in many characters. In such quanti- 
