1922] 



Setchell-Goodspeed-Clausen: Nicotiana Tabacum 



489 



Segregation for flower color was studied by the method described above. 

 The color distinction between red and pink was sharp and easily drawn. 

 In the pinks, however, there was a continuous series of shades from 

 the deep rose pink characteristic of F^ to the light pink typical for 

 angustifolia. Numerical data are given in table 5. 



TABLE 5 



Fj SEGREGATION OF PINK AURICULATA X RED SESSILIFOLIA. 



In 1918 in connection with flower size studies three more popula- 

 tions of FoHj, were grown. Leaves were collected from each plant 

 and pressed, and leaf shape studies were made on these preserved 

 specimens. The studies were not so satisfactory as those made in the 

 field, where it is possible to examine all the leaves on a given plant ; 

 nevertheless, the data derived from the studies agreed substantially 

 with those obtained in 1916 from field studies. It was noted in these 

 studies that there was a distinct class of "attenuated" leaves similar 

 to those which have been described in previous populations. Both 

 attenuation and constriction were observed to occur in the leaves of 

 some individuals, and this gave rise to some difficulty in classification. 

 Numerical data are given in table 6. 



TABLE 6 



F2 SEGREGATION OF SESSILIFOLIA X AURICULATA. 



