THE STEM OR SHOOT. 



83 



(Sedum reflexum), amongst Dicotyledons, Celakovsky 

 lias clearly and beautifully demonstrated another in- 

 teresting type of true dichotomy in Lonicera Pericly- 

 menum (fig. 23) ; but many other plants will show the 

 same phenomenon under similar circumstances. Where 

 a leaf dichotomizes deeply, its axillary bud follows 

 suit, so that, as a result, two leaves, each with its 

 axillary bud, appear, where before there was only one 

 (fig. 23 a and b). In the case of the leaf different 



* I 



Fig. 22. — Msesa ramentacea. Dichotomy of the stem. 



stages between apical forking and its complete division 

 into two leaves are all present on different shoots, or 

 on different parts of the same shoot, as mature 

 structures ; in the case of the bud only the final stage, 

 viz., that of its complete division into two buds, is 

 represented. But it is obvious that this is a case of 

 congenital dichotomy of a single shoot in its youngest 

 or bud-stage. The ontogeny would never have 

 revealed this, but would simply have told us that two 

 collateral bads arise in the axil of a deeply-divided 

 leaf. Only by the comparative method of investigation 

 can we definitely determine that dichotomy of a single 



