134 BOTANICAL GAZETTE. [May, 



OPEN LETTERS. 



The Origin of Floral Structures. 



I am always glad to receive criticisms of my theory from an oppo- 

 nent, but my reviewer, " R.," somewhat misrepresents me rather than 

 criticizes, for he says (Bot. Gaz. xiii, 324) : " The Darwinian theories of 

 natural selection and of cross-fertilization are thus wholly repudiated." 

 My exact words are (Or. of Fl. Str. p. 336), " I do not wish the reader to 

 suppose that my theory is altogether in opposition to Mr. Darwin's." I by 

 no means reject natural selection, and even give the result of an experi- 

 ment showing how a hard Russian wheat when sown thickly with a soft 

 English grain was "selected," as that only carried ears. I adopted the ex- 

 pression " constitutional selection " as best describing that kind. I recog- 

 nize natural selection as a factor in several ways, but never as a cause, and so 

 not having the importance which has generally been attached to it. None 

 of my many reviewers have credited me with denying it, either in Eng- 

 land or America, except " R." " R." quotes the Papilionaceae as opposed to 

 my theory, in having the standard larger than the anterior petals ; but 

 this agrees with well nigh all irregular flowers in which the stamens af- 

 ford the landing place, e. g., Pelargonium (except " the Scarlets "), Rhodo- 

 dendrons, horse-chestnut, Ama?yllis, etc. I have attributed this result in 

 part to atrophy of the anterior petals (p. Ill) without precluding a cer- 

 tain amount of hypertrophy on the opposite (dorsal or posterior) side (p. 

 116). " R." must have overlooked what I have written on this as well as 

 on the resupinate labellum of Orchis (p. 107). " R." assumes Verbascum 

 to be a further advance of the Personales. I regard it as an ancestral 

 form and as more nearly approaching the primitive and regular type of 

 flower; for I know of no case where an irregular flower passes into a 

 regular one except in a pelorian condition (see chap. xiv). This Verbas- 

 cum most certainly is not. Why " R. ; ' calls zygomorphic types " ancient " 

 does not appear. This is one difference of importance between our re- 

 pective views, in that I ventured to offer my theory as suggestive or as a 

 "working hypothesis" only (p. 3); on the other hand, " R." states his 

 opinions in a very categorical manner, as if they were not open to doubt 

 at all. Thus he says: "Although it is evident that natural selection must 

 act"— why "evident"? why "must"? I agree with Prof. Huxley, who 

 says that a scientist does not know the word " must." If " R." had pointed 

 out how natural selection produces a combination of minute characters 

 in all the organs of a flower, including the floral receptacle ; and all in 

 harmonious correlation with insect fertilization; I should have been glad 

 to have read it (see p. 330) and his review would have been more satis- 

 factory ; but merely to say natural selection " must " have brought them 

 about is neither an answer nor a criticism. 



I can only add that I am extremely gratified to find that the views of 

 such able naturalists as Prof. Packard, A. W. Hyatt and others to be thor- 

 oughly in accordance with my own. I had no conception that neo- 

 Lamarckism was so widely sustained in the United States. 



London, England. George Henslow. 



I am satisfied to leave the reader with the context of Prof. Henslow's 

 quotation: " Instead, therefore, of using this term (natural selection) as 

 the cause of anything and everything, I prefer to attribute effects to 

 hypertrophy, atrophy, resistance to strains, responsive action to" irrita- 



