The Mode of Origin and the Vascular Supply of the 
Adventitious Leaves of Cyclamen. 
BY 
L. A. BOODLE. 
With six Figures in the Text. 
^jPHE mode of origin of the adventitious leaves which arise near the 
JL margin of the cut surface of decapitated seedling-tubers or hypocotyls 
of Cyclamen 1 has been studied at various stages of their development, and 
the evolution of the vascular supply to these adventitious leaves has been 
traced by means of longitudinal and transverse sections. 
The first stage in the formation of an adventitious leaf can be recognized 
by the appearance of division-walls in a small group of cells belonging to 
Fig. i. Rudiment of adventitious leaf as seen in a transverse section of the tuber, x 250. 
the first layer beneath the epidermis of the young tuber. The first division- 
walls are tangential ; and then further subdivision of the cells takes place 
by means of walls in different directions. Growth accompanies these 
divisions, a lenticular mass of small cells being produced (Fig. 1). At this 
stage only a minute external prominence is caused, but the latter increases 
in size, owing to continued growth and cell-division, and soon, e. g. when 
0*2 mm. in length, bears on its surface a number of short glandular hairs, 
similar to those found on the young cotyledon, tuber, &c. These hairs 
being crowded together on the leaf-rudiment, make it easily visible. 
1 These leaves mostly grow from the uninjured surface of the tuber, a short distance below the 
margin of the cut surface. 
[Annals of Botany, Vol. XXXIV. No. CXXXVI. October, 1920.] 
