214 Varietäten, Descendenz, Hybriden. 



the leaf-factor being respectively less than 2 or greater than 3. The 

 hybrid between two such types has an intermediate value. In F 2 a 

 continuous series of types occurs, which, however, forms a trimodal 

 curve and the proportion of individnals grouping themselves about 

 the three modes is 1 : 2,2 : 1. 



Type of branching and the length of the vegetative 

 period. The flowers of Gossypütm are borne on leafy cymes; in 

 the sympodial types the flowering period commences with the de- 

 velopment of the secondary branching, while in the monopodial 

 types this period is delayed until the tertiary branches are deve- 

 loped. There is thus a definite relation between the habit and the 

 time of flowering. The actual duration of the vegetative period, 

 which preceeds flowering, varies with circumstances, for which a 

 correction must be made in comparing crops of different years or 

 crops grown under different methods of cultivation. Nevertheless 

 this character appears to be more reliable for the purpose of recor- 

 ding the habit of the plants under consideration than is the direct 

 record of the percentage of monopodial secondary branches. The 

 length of the vegetative period of the F x generation is intermediate 

 between those of the monopodial and sympodial parents. It does 

 not, however, correspond with the mean of the two parental values, 

 but in all cases approaches the sympodial t3^pe. The F 2 plants form 

 a continuous series in which every stage from early to late flowering 

 is represented. The curve has only one mode and the results would 

 appear to indicate partial dominance in F 1 with incomplete resolu- 

 tion in subsequent generations. There is, however, a considerable 

 and undetermined experimental error and it is further to be noted 

 that a correlation has been found to exist between the presence of 

 red pigment and the length of the vegetative period. In the con- 

 struction of the monomodal curve no distinction was made between 

 pigmented and non-pigmented plants and it would appear possible 

 that a Separation of the plants into two groups, dependent on this 

 character, might disclose two trimodal curves, whose presence is 

 obscured through superposition. 



Leaf glands. It is easy to recognize two distinct types in which 

 the leaves are either all eglandular or all glandulär. In the glandulär 

 forms there may be 1—3 glands per leaf and the number of glands 

 may vary in the different leaves of the same plant. It has been 

 found possible to isolate and grow in a State of purity forms in 

 which the leaves are eglandular and forms in which the majority 

 of leaves bear three glands. Plants in which the majority of leaves 

 have 1 gland, but those of the main stem have 3, have invariably 

 given mixed offspring. Types in which nearfy or quite all the leaves 

 have one gland may occur as intermediates between the eglandular 

 and glandulär types, but it would appear that they may also occur 

 as a pure form. 



Correlation. Besides the correlations alluded to above, a cor- 

 relation has been found to exist between the colour of the flower 

 and the size of the petal. If the petals be white in colour, they will 

 be small and hardly project beyond the bracteoles; if they be yellow, 

 they will be large and about twice the length of the bracteoles. 

 The presence of the red pigment does not affect this correlation, 

 so that red-on-white flowers have small petals, red-on-yellow large. 



R. P. Gregory. 



