SUBSTITUTION OF AXIAL FOR FOLIAR ORGANS. 547 



" I was in some doubt whether the petals or the stamens were 

 developed. In cases of imperfect transformation the petals at 

 the base of the umbellule seemed to stand in the position of 

 calyx or involucrum, giving the idea that the stamens were de- 

 veloped into flowers. But in the case where there were six flowers 

 developed there were no petals at the base. 



" That it was a matter of extra nutrition was shown by this : — 



" 1. That they were cultivated as garden flowers. 



" 2. That where there was one perfectly developed umbellule, 

 it was the only one in the umbel. 



" 3. That where there were three umbellules they were all im- 

 perfect. 



" 4. That in this imperfect umbellule the perfect flowers were 

 on long stalks and the imperfect ones sessile. 



" 5. That the umbellules were on stalks both longer and 

 thicker than those of single flowers." 



[Concerning the foregoing argument at large an expert 

 writes : — " The abnormalities you describe certainly show that 

 an axis may arise abnormally in the place of a normal leaf- 

 structure, and every modern botanist would be in agreement 

 with you in your criticism of the older form of the doctrine of 

 axillary buds. I think we are largely emancipated from the 

 dextrous juggling with the arrangements and relations of organs 

 which used to pass current as morphology. 



"You have quoted sufficient evidence in the text (§ 190) to 

 establish the conclusion that no sharp line can be drawn between 

 axes and leaf-structure ; and a very great deal more could be 

 added in the same sense. Petioles for instance, exist which the 

 most highly trained histological observer could not distinguish 

 from stems. 



" But I must demur to the suggestion that the replacement of 

 one by the other is primarily a question of nutrition. We are 

 as ignorant as ever of the proximate cause of the production 

 of a leaf or a shoot at a certain spot in meristematic tissue." 



To this last remark I had at first made only the reply that the 

 plants exhibiting the abnormalities were in all cases excessively 

 luxuriant in their growths ; but to this I am now able to add a 

 more definite reply. The expert from whom I have just quoted, 

 had read this appendix before there had been made to it the 

 above addition describing the flower from Dieppe ; and I was not 

 myself aware, until I came to read over this addition, what clear 

 evidence it contains that extra nutrition was the cause of these 

 transformations of foliar structures into axial structures ; but 

 the above paragraphs 1, 2, 3, 4, 5, contain different evidences 

 conspiring to prove this.] 



