TH K LEAF. 



187 



floral axis, whose apical bud is usually suppressed, and 

 which bears only two rudimentary carpels. The elon- 

 gated stalklet of the ovule of Ginglco occasionally deve- 

 loped is not simple outgrowth, as has been considered 

 by some authors, but is the petiole of the carpellary 

 leaf developed alternately along the floral axis." " The 

 formation of ovules upon the foliage-leaves of Ginglco 

 reminds us of the carpellary leaves of Cyras, and the 

 ovules are in both genera marginal formations of the 

 sporophyll." These generalizations and comparisons 

 may' certainly be accepted. 



In both these phenomena, viz., staminody and car- 

 pellocly of the foliage-leaves, we see an excellent 

 instance of the flood of light which abnormalities often 

 throw on the real nature of certain structures which 

 is otherwise, under normal conditions, utterly obscure. 



Lutz observed and figured a very rare case, viz., 

 foliage-leaves of a crocus (whose flowers and bracts w r ere 

 unusually affected by carpellody) bearing each a stigma 

 at its tip (PI. XIII, fig. 2). Many botanists would 

 explain this by supposing that, the balance of the 

 plant being upset, the primitive potentiality resident 

 in the protoplasm of all its parts to form any kind of 

 organ at any time, became raised into actuality when 

 certain abnormal conditions afforded the required 

 stimuli. It is preferable, on the other hand, to hold 

 the Yiew that no organ can assume the characters (or 

 some of them) of another organ unless it has had, with 

 that organ, a common origin in the past. Apart from 

 that common origin there is, owing to the stereotyped 

 morphological and physiological nature of the (in time, 

 position, and function) widely-separated organs, no 

 likelihood of their exhibiting similar features. The 

 abnormal crocus-leaf, i. e. assuming the observation to 

 be correct, may be explained by postulating a fern-like 

 foliage-sporophyll as the original common ancestor of 

 both foliage-leaf and carpel, of which we see, in the 

 case before us, a dim reminiscence, expressed, of course, 

 according to the idiosyncrasy of the particular plant con- 



