METAMORPHOSIS. 



163 



far as the base where the inner margins so-formed 

 grew out as a pair of leaf-lobes whose inner margins 

 became united with those of the main leaf resulting 

 from its dichotomy, and, at the same time, with the 

 two inroUed margins of its apical portion ; the 

 two lobes of the dichotomized main leaf then becoming 

 reunited, a structure would result supplying the 

 two median ventral laminee into which it has been 

 shown that the median anther-loculi may become 

 transformed. The dichotomy, with the exception of 



los 



Fig. 126. — Vlmus sp. (Elm). Dichotomized foliage leaf with infolding 

 margins of the apical lobes, us, upper surface ; Is, lower surface. 

 (G. S. Saunders.) 



the apical portion, he regards as not externally visible, 

 but as internal. 



This may well be the explanation of anther-structure. 

 In a deeply-dichotomized elm-leaf the inner margins 

 of the two lobes tended to become bent inwards; if this 

 were to proceed farther and the surfaces adjoining the 

 margins fused, anther-structure would result (fig. ] 26). 

 Celakovsky has also described and figured abnormal 

 bracts of the hornbeam showing the same congenital 

 forking and marginal infolding as in the Hieracium- 

 leaf, yielding two median lamellae; in this case they 

 are on the dorsal surface, and the structure is quite 

 unequivocal. "While this is a highly probable method 



