1922] Setchcll-Goodspecd-Clausot : Nicotmna Tabacum 505 



resemble those of macrophylla in shape but differ from them particu- 

 larly in the basal portion. The corollas are white with a yellowish 

 tinge ; but in shape, size, and general proportions they are very similar 

 to those of macrophylla. Line drawings of typical features of alha 

 are reproduced in plate 82. The reproductions of photographs of the 

 leaf of alba and of the Fj hybrid of the alha-macrophylla series are 

 shown in plate 84. 



Macrophylla, U. C. B. G. 22/07, has been described above. 



In these two varieties there are definite character contrasts in color 

 of flowers, macrophylla being red and alha white ; and in stature, 

 macrophylla being low of stature and alba distinctly taller. Other 

 contrasts also exist, although they are not so definite, in the style of 

 branching and in the shape and texture of the leaves. Like those 

 which have been considered above, this is a hybrid series in which 

 the contrasts between the parent forms are of a distinctly complex 

 character. 



2. F, OF THE ALBA-MACROPHYLLA SERIES 



The crosses between alba and macropyhlla were made in July, 1909. 

 The cross was successful in both directions, and seed was secured from 

 alba^ X macrophylla^, which was given the number Hoo, and from the 

 reciprocal which was given the number H24. 



When mature the F^ plants were tall, 100 to 200 cm., averaging 130 

 to 160 cm. Habit and leaf shape were in general those of alba. The 

 corolla was deep pink of about the same shade as that of the F^ of 

 the angustifolia-macrophylla series. The variation in height in these 

 populations possibly indicates a lack of constancy in the alba parent 

 in this respect. In plate 83, figure 2, is shown an F^ plant of lOFiH.^. 



3. F, OF THE ALBA-MACROPHYLLA SERIES 



In 1911 four F. populations were grown, viz., 25 plants each of 

 llF,H,3Pi;„ llF,H,3P,i, and llF.IL.Pe, and 23 plants of 11F,H,,P.,,. 

 The four populations, although small, proved to be equivalent in every 

 respect. The type of segregation was very complex. That of differ- 

 ences in types of leaves, especially, presented such a series of inter- 

 gradations as to defy any definite classification. Likewise in height, 

 there was a continuous series of forms from the tallest to the shortest, 

 A rough classification was, however, made for purposes of reference 

 into tall, medium, and short. An excellent illustration of the segre- 

 gation for this character is shown in plate 85, figure 1, which shows 



