THE LEAF. 



155 



of which the bracts are very well developed and 

 foliaceous. 



The observation by Velenovsky and Domin of the 

 reappearance of leafy bracts (accompanied -by vires- 

 cence and other changes in the flowers) in the winter- 

 cress (Barbarea vulgaris) is interesting, for in one 

 species, viz., B. bracteosa, bracts occur as a normal 

 feature. 



In Cephalotaxus the writer observed, in slightly 

 proliferated female flowers, the abnormal occurrence 

 of two superposed pairs of small foliar organs situated 

 in the transverse plane immediately below the two 

 ovules (fig. 41 c). It is probable that, owing to lack 



a b c 



Fig. 41. — Cephalotaxus drupacea. Diagrams of a normal flower (fe) 

 and two abnormal "flowers" (a and c). 



of adequate space, a median whorl or two, which might 

 otherwise have developed, has been suppressed. It is 

 highly probable that these basal scale-leaves represent 

 the reappearance of structures which were once present 

 in the flower of Cephalotaxus before it became so greatly 

 reduced, and that they correspond to the two to three 

 pairs of scale-leaves (bracts) which occur normally on 

 the floral axis below the ovules in Taxus and Torreya. 



The articulation in the axis of the male flower of 

 Euphorbia, probably, as Celakovsky points out, marks 

 the position of bracteoles which have become sup- 

 pressed. In some abnormal cases these have been 

 found to reappear. Abnormal specimens of the dande- 

 lion (Taraxacum officinale) and daisy exhibit scapes 

 bearing one or more foliar organs ; the same has been 

 seen in a species of Leontodon and in the lily-of-the-valley 

 (Convallaria majalis), etc. ; in this connection it is to 



