PROF. OLIVER ON THE STRUCTURE OF THE ANTHER. 425 



margin, upon each side of the median nervure, as is well shown, in stages intermediate 

 between the stamens and petals, in Atragene alpina (taf. xiii. 316 B.). Upon each of 

 the two lobes of thickened parenchyma a longitudinal suture is found, which answers to 

 their line of dehiscence. That this line does not correspond to the leaf-margin he further 

 endeavours to show from a monstrous flower of Colchictmi (p. 336, taf. xiii. 319). Trevi- 

 ranus * considers Bischoff's modification required to suit Cassini's theory to nature. He 

 concludes his observations on anther-morphology, however, thus : — " Dass jedoch dieses 

 nicht als allgemeines Bildungsgesetz aufgestellt werden konne, zeigt z. B, Paris, wo au- 

 genscheinlich der Pollensack durch den Band des zu einem Trager verschmalerten Blu- 

 menblattes, und die beiden Klappen von den beiden Oberflachen desselben gebildet werden." 

 With regard to Paris, vide infra, p. 427. H. v. Mohl's paper, referred to above, contains 

 an excellent exposition of the state of the question of anther morphology. The cases 

 which he especially refers to of metamorphosis of stamens into carpels — the anther- 

 sutures becoming ovuliferous— do not, as he himself observes, afi'ord conclusive evidence 

 in favour either of the theory of Cassini or that of Bischoff. The circumstances alluded 

 to by Roeper, of the red colour of the leaf-margin of certain Euphorbiacese being found 

 again in the anther-suture, and the presence of cilia on edges of leaves and on the lines 

 of sutm-e in the anther. Von Mohl admits to be very important, if not decisive, evidence 

 that the latter answer to the leaf-margins in some cases; while, on the other hand, 

 transitional forms presented by the Rose, as cited by BischoflP, by the Poppy, and Nigella 

 damascena, incontestably show that the anther-cells in these plants do not originate 

 opposite to each other in the leaf-parenchyma on each side of the midrib of the leaf, but 

 at distinct points on the face of the lamina— the anterior cells nearer to the median 

 line, the posterior to the margin. In N. damascena, described by Von Mohl, the ante- 

 rior cells are parallel to the midvein, the posterior and marginal cells having their 

 lower extremities contiguous to them, while their upper ends are remote. H. von 

 Mohl does not commit himself exclusively to either view of anther- structure in this 

 essay. 



Mr. Bentham has kindly called my attention to the observations upon the homology of 

 the anther-cells contained in a review of Dr. A. Gray's " Genera of the Plants of the United 

 States"!. The reviewer considers that the anthers are homologous with the 'glands' which 

 frequently occur at the top of the petiole, or near the base of the limb, in several genera 

 of Dicotyledons, remote in the order of their natural afiinity. He says, " In the leaves 

 forming the andrcecium a partial return to the system of stem-leaves takes place, inas- 

 much as the filament is entirely reduced to the vascular system, its glands are converted 

 into anthers, and the cellular parenchyma is only occasionally represented in an expanded 

 connectivum, or slight membranous expansion of the filament." I have not made the 

 minute structure of these curious appendages my study ; I have merely inspected them 

 with a lens in Mceococca, Aleurites, and allied genera of Euphorbiacefe, and in Pithecolo- 

 bimn. 1 must acknowledge, however, that I am unable to view the question of their 

 homology in the same light with the reviewer, whose theory appears to rest ixpon a 

 curious analogy in respect chiefly to the position of these glands and anther-lobes, rela- 



* Phys. (1. Gewachse, i. p. 277. t Ke" Misc. vol. i. (1849), p. 3j9. 



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