Edith K. Saunders 217 



The leaves which succeed the cotyledons are also glabrous except for one 

 or two minute marginal hairs near the apex. But as the plant develops 

 the successive leaves attain a greater degree of hoariness until the lower 

 surface becomes covered nearly if not quite as densely as in the fully 

 hoary type plant, though on the upper surface the covering of hairs 

 remains throughout appreciably thinner. As we ascend from the vege- 

 tative region of the stem to the bractless racemes hairs usually gradually 

 extend down on to the axis from the pedicels which become distinctly 

 hoary on their abaxial surface. In the smooth-stemmed Foxglove, as 

 stated above, the stem is glabrous, deep green and of a polished appear- 

 ance from the radical rosette upwards. The leaves, though hairy on both 

 surfaces, are distinctly less so on the upper surface than in the hairy 

 form, and are deeper green in colour. The midrib on the under side of 

 the last-formed leaves of the rosette appears as a smooth green demar- 

 cation line halving the greyer lamina and petiole, whereas, in the hairy 

 form, the grey surface appears unbroken. This feature serves as a 

 useful means of identification in young plants which have not yet de- 

 veloped the flowering axis. Proceeding up the stem we find that an 

 overflow as it were of the hairs from the leaf may extend down from the 

 point of insertion as a hairy streak or band. As we approach the flower 

 spike these decurrent bands from the uppermost leaves and bracts 

 coalesce more or less completely so that the axis becomes as completely 

 downy as in the hairy form. Thus in both Stock and Foxglove we have 

 the same feature, a transition from the glabrous condition characteristic 

 of the vegetative region to a more hairy condition in the inflorescence, 

 the change being much more marked however in the Foxglove. 



As appeared probable from the results obtained incidentally in the 

 course of the earlier experiments on heptandry the smooth-stemmed 

 form in D. purpurea is found to behave as a simple dominant. The 

 statistical evidence proving this to be the case is given in the accom- 

 panying tables where it will be seen 



(1) that both forms, when pure, breed true ; 



(2) that the F^ generation from a mating between the two is all 



smooth-stemmed ; 



(3) that F^ plants yield the simple ratio of 3 smooth to 1 hairy 



when self-fertilised, and 1 smooth to 1 hairy when crossed 

 back with the hairy form. 



These results are in marked contrast to the complex relations which 

 are found to hold in the Stock, a full account of which it is hoped to 



