208 RET. G. HENSLOW O^ THE CAUSES OF 



j)anu7a, Convolvulus^ Prijnula, &c., as well as apocarpous pistils in 

 flowers whicli are normally syncarpous. 



As examples o^ solution are polysepalous aud inferior calyces of 

 apples and Umbelliferous plants associated with hypogynous petals 



and stamens. 



The immediate cause of the solution in these cases is the arrest 

 of development of the receptacular tube, lu consequence of which 

 the ovary remains superior and the calyx free. 



II. HxPERTnopHT. — As efFccts of a superabundance of nourish- 

 ment which must De expended in the development of superuume- 

 organs, I would class : 



1. Poli/phylly (Z. c. p. 358); aud of this phenomenon two varieties 

 may be recognized. 



i. The increase in number of some of or all the individual 



organs of a whorl, 

 ii. The "symmetrical increase " of whorls. 



2. Restoration to a higher ancestral number. 



Firsts any single organ may be doubled, trebled, or replaced 

 by several. Thus two stamens often arise from the same gland 

 in the place of one lateral stamen of a cruciferous flower. A 

 similar phenomenon appears to occur normally in Buto)7ius. 



Secondly , of what I call the symmetrical increase of whorls, 

 there are innumerable examples. In fact, any flower, say normally 

 «-merous, seems capable of becoming w + 1-, w + 2-, w + &c.-inerous ; 

 Elder, Jasmine, Puchsia, &c. may be mentioned. 



Thirdly, as partial or entire restorations to an ancestral num- 

 ber, which is normally reduced, are leguminous flowers with two 

 to five carpels. Poppies with three sepals and six petals are, aa 

 I believe, reversions to an ancestral trimerous arrangement- 



The development of the stamens of Hypericum would seem to 

 show that the terminal staminal papillae are themselves early ar- 

 rested, but give rise to a cluster of smaller lateral papillse, each 

 of which becomes a perfect stamen. 



3. Fleiotaxy (/. c. p. 371), This term applies to an increase : 

 i. In the number of whorls. 



ii. In the number of cycles. 

 Examples of increase of whorls is seen in the multiplication of 

 the bracts of the Wheatear Carnation, in the perianth of the 

 double White Lily, in double Campanulas, &c., and in Stone- 

 crops with an extra staminal whorl. I would include here the 

 double Dajffodil, the successive whorls of which undergo partial 

 adhesion as well as partial dialysis at the same time. 



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