IV. THE EXPERIMENTAL RESULTS. 



The material used in these investigations formed part 

 of the types, isohited in 1909, which have since been maintained 

 in pure culture. Since at the time these experiments were begun 

 nothing was knowai concerning the correlation or interdependence 

 of the various characters in tobacco, it was decided to make a 

 preliminary survey of the inheritance of practically all the 

 characters which deal with the stem and leaves. This was done 

 partly with the object of ascertaining how far the inheritance of 

 the individual characters could be studied independently, and 

 partly to determine the most suitable methods of investigation. 

 It is hoped to follow this preliminary account by a more 

 comprehensive study of the more important characters. The 

 characters which have been considered in the present investi- 

 gation are (I) time of flowering, (2) height of stem, (3) arrange- 

 ment of the leaves on the stem, (4) length of the decurrent 

 portion of the lamina, (5) venation of the leaf, (6) leaf-shape, 

 (7) undulation of the surface and margin of the leaf. 



In all, five crosses have been made. Type 9 < Type 51, 

 Type 16 Type 35, Type 23 x Type 38, Type 2 x Type 3, and 

 Type 2 x Type 51. The first, that between Type 9 

 and Type 51, has been carried to the F4 generation, those 

 between Type 16 and Type 35 and Type 23 and Type 38 to the 

 F3 generation. Only the F, generation has so far been raised 

 of the other two. It will be seen from the photographs of 

 Type 9 and Type 51 (Plates I and II), and from the full 

 description of the types reprinted as an appendix to this paper 

 (p. 108), that these two forms differ in almost every character, 

 from hoiglit of plant to the mode of pollination and colour of 

 the corolla. 



