204 lock: 



identical conditions until the seedlings were about 2 inches 

 across. The larger plant (A) was one of a number of similar 

 individuals, which were then set out in ordinary garden soil at 

 intervals of 18 inches by 24. At the same time the other 

 plant (B) was potted, and continued to grow in a greenhouse 

 imtil the time when the photograph was taken. 



The flowers of the two plants differ very slightly, those of 

 B being a little the smaller. On the other hand, the differ- 

 ence in habit and inflor3scence may readily be estimated from 

 the photograph. In size and shape the leaves of A are closely 

 similar to those of the parental variety of N. tabacum 

 grown side by side with it, whilst the leaves of B are nearly 

 of the same size and shape as those of N. glauca when 

 similarly grown in a greenhouse . The texture of the leaves 

 was more or less intermediate, but decidedly different in 

 A and B. 



All the F 1 plants resulting from crosses between various 

 species carried out in 1906 were grown in 1907. Some of each 

 kind were kept in a greenhouse, and others were planted out in 

 the open air, precisely in the same manner as has just been 

 described in the case of the cross N. tabacum X glauca. Differ- 

 ences similar to those mentioned in the case of the differently 

 treated individuals of that cross were to be seen in every case, 

 though usually less pronounced. All the illustrations to this 

 paper, with the exception of the larger plant shown in Plate I., 

 w;ere taken from specimens grown under glass throughout. 

 On the other hand, the descriptions of the F 1 plants were taken 

 in every case from the presumably more " normal " individuals 

 grown in the open air after germinating under glass. The 

 seed from which the plants described in the F2 generation 

 were grown was taken in nearly all cases from greenhouse 

 plants, because with these the greatest certainty with regard 

 to parentage was obtainable. Seed was also taken from open 

 ah' plants for comparison, but no appreciable difference was 

 found between the offspring of parents which showed the 

 most marked " acquired " differences. Nor could any differ- 

 ences of imjiortance be recognized between plants of similar 

 constitution grown in tlie open at Cambridge in 1907 and at 

 Peradeniya in 1908. 



