172 PROCEEDINGS OF THE ACADEMY OF [1897. 



Facts of this character are common, but this case presents them 

 in such a remarkable degree, as to make it a special one Helio- 

 phytum indieum, a self-fertilizer and wonderfully productive, has 

 maintained a remarkable homogeneity amidst rare variation in the 

 environmental conditions. 



If we accept the thought frequently thrown out in these contribu- 

 tions that form results from the various degrees of rhythmic energy 

 in the plant itself, just as it would in the formation of the frost 

 crystals on a window pane, we can see that environment can not be 

 regarded as a leading agent, but must take a minor place. 



THE ORIGIN OF THE FORMS OF FLOWERS. 



In my intercourse with intelligent and observing botanists, who 

 frequently do not place their conclusions on record, I find a grow- 

 ing tendency to discredit views, till recently widely prevalent, that 

 external conditions have any more than a feeble influence on the 

 evolution of the forms of flowers. Thought is in the direction that 

 various degrees of internal energy seem rather the chief agents in 

 effecting change. 



Listening to some verbal remarks before the Botanical Club of 

 the American Association for the Advancement of Science, at 

 Buffalo, New York, by Mr. David F. Day, I was struck by his 

 point that irregular flowers were usually associated with the curving 

 or twisting of the peduncle, while regular flowers and straight pe- 

 duncles were usually closely related. I saw this subsequently well 

 illustrated in lilies. In the class to which belong Lilium Philadel- 

 phicum and L. Catesbcei, the upright flowers are perfectly regular ; 

 irregularity, in some of the floral parts, characterizing the nodding 

 ones. The nodding peduncles, after flowering, become erect, and in 

 the seed-bearing stage the seed vessels are erect on perfectly straight 

 peduncles in both classes. It is evident from this fact that in the 

 species with drooping flowers, the expansion of the perianth occurred 

 before the uncoiling energy had been exhausted, and during a 

 rhythmic rest. It is further evident that the growth-waves prevail- 

 ing in the development of the flower varied in intensity in different 

 parts, and that varying forms must necessarily follow from these 

 varying degrees of energy. Unequal pressure by reason of the 

 curve ought to be accountable for this inequality. It is, however, 

 evident that outside agencies could not have had much, if any, in- 

 fluence in the curving which results in irregularities of these lilies. 

 Some excellent illustrations are often seen where an erect flower oc- 



