64 EEV. G. HENSLOW — HOMOLOGY AKD 



Homology of the Stamens. — That a stamen is homologous with 

 a leaf is obvious from the many cases in which it is transformed 

 into a leaf-like organ, as a petal or true leaf. But whether the 

 filament corresponds to the petiole, and the anther to the blade, is 

 not always determinable. The water-lily shows that a petal, 

 possibly representing the petiole or the lamina, passes into a 

 stamen by a narrowing of the basal part ; but in abnormal fuchsias 

 the anther alone may be converted into a blade, from which it 

 might be inferred that, in this case the filament was a petiole. In 

 the green rose the anther is often borne on a leaf-blade, which tapers 

 into a petiole below. 



Progressive changes in the Andrcecium. — Pidilloid stamens. Under 

 this heading it is proposed to include modifications of stamens 

 which take on more or less perfectly the form if not the functions 

 of the pistil. These metamorphoses are much more frequent than 

 of the perianth into pistilline structures ; for that a very close 

 homology exists between the stamens and pistil has been long 

 recognised, as shown by Robert Brown,* De Candolle, and 

 others. 



Of the changes undergone by the stamens, Dr. Masters observes 

 that " in some cases the whole of the stamen appears to be 

 changed, while in others it is the filament alone that is altered, the 

 anther being deficient, or rudimentary ; while in a third class of 

 cases, the filament is unaffected, and the anther undergoes the 

 change in question." The following examples may be taken to 

 illustrate these changes experienced, respectively : — 



The filament has been observed to be more or less "ovarian," 

 bearing rudimentary ovules in Begonia,] Primula,^ Papaver,^ 

 and Fuchsia.^ 



The anther may become ovarian, as is often the case in Semper- 

 vivHin,^ Bego7iin,-\ and Salix;^'^' while the ovules thus borne by 

 anthers may themselves produce pollen, as in Posa arrensis. f f 

 Such an ovule may be converted into a stigma, as described by 

 Miiller in the case of Begonia.] 



The anther may assume a stigmatic form, as in Papaver,^ or be 

 styhform, as in the bamboo. |J 



Tiie connective assumes a stigmatiform structure in Begonia \ 

 and Thalictrum minus. ^^ 



The complete substitution of carpels for stamens occurs in many 

 plants, as in Mains apetala,\\\\ the minor stamens of Magnolia, of 



* 'Trans. Lin. Soc.,' vol. xii, p. 90. 



t ' Bot. Zeit.' 1870, p. 150, taf. ii. ; ' Journ. Lin. Soc' Botany, vol. xi, p. 472, 

 1871 ; 'Gardeners' Cliron.' 1876, vol. vi, p. 239. 



X Masters in 'Trans. Lin. Soc' 2nd. Ser., Botany, vol. i, p. 285; and Hen- 

 slow in ' Jonrn. Liu. Soc ,' Bot., vol. xvi, p. 210. 



§ 'Teratology,' p. 304. || I. c. j). 198. H I.e. p. 309. 



** ' Ann. Nat. Hist.' 2nd Ser., vol. xviii, p. 254. 



tt 'Journal of Botany,' JVov. 1867, p. 318, tab. 72. 



+ + Gen. Mimro, 'Trans. Liu. Soc,' vol. xxvi, p. 7. §§ 'Terat.,' p. 307. 



III! Poiteau et Turpin, ' Arbr. fruit.,' t. xxxvii, referred to by Moquiu-Taudon 

 in his ' Teratologic,' p. 220, where other cases are given. 



