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THE AMERICAN NATURALIST [Vol. XL VI 



Yellow was completely dominant to its absence and to pale yel- 

 low. Red was incompletely dominant. The very interesting 

 fact developed that although yellow behaved as an allelomorph to 

 its absence in crosses with white, it was also allelomorphic to pale 

 yellow in crosses with the latter. This indicates that pale yellow 

 is simply a modified form of yellow, a fact in entire accord with 

 my teleone theory of Mendelian inheritance, and opposed to the 

 de Vriesian idea of the immutability of the so-called unit charac- 

 ters. An interesting ease of correlation was found. White (ab- 

 sence of yellow) is hardier than yellow. 



In shape of leaf Leake uses as an empirical means of describ- 

 ing leaf shape a formula which is essentially the ratio between 

 the length and breadth of the central lobe. The pure races (and 

 the author took the pains to work with pure races) may be di- 

 vided into two groups with reference to this "leaf factor," 

 namely those in which it is less than 2, and those in which it is 

 greater than 3. No cases were found in pure races in which the 

 value of this factor was between 2 and 3. F x between these 

 groups gave intermediate leaf factors. F 2 apparently behaved 

 as if the cross involved a single gene, but fluctuating variation 

 obscured the results considerably. Crosses between ~F 1 and 

 either parent form gave only the intermediate and the one par- 

 ent form, the same difficulty appearing from fluctuation in the 

 character. This strongly confirms the conclusion that a single 

 gene is responsible for the difference between these two groups. 



Earliness of flowering X late flowering proved to be a very in- 

 teresting study. The author had previously discovered that 

 types with sympodial secondary branches flower early, while 

 those having monopodial secondaries are late flowering. This re- 

 lation had also been noticed by others, the early or late flowering 

 being a result of the manner of branching. Length of vegetative 

 period (time between planting and first flower) proved to be 

 highly fluctuating, varying widely as between different seasons. 

 F, between the monopodial and the sympodial types was inter- 

 mediate between the parents, but nearer the sympodial (early) 

 parent. F 2 gave a continuous series extending from the early 

 parent nearly to the late parent, the frequency curve for the 

 earliness in the F 2 population being monomodal. While the 

 author does not pursue the subject further, it may easily be 

 shown that this is exactly what Mendelian theory calls for on 

 the assumption that several factors, each alike in effect, their 



