PROF. OLIVER ON THE STRUCTURE OF THE ANTHER. 427 



usual form of anther, and we find that an exceptional mode of dehiscence, by valves 

 opening from below, characterizes the order*. With regard to Paris, referred to by 

 Treviranus [supra, p. 425), I have examined several species (P. quadrifolia, P. hexaphylla, 

 P. obovata, P. incompleta, and P. polyphylla-\) ; and I certainly cannot agree with the 

 opinion expressed by him, that the valves of each anther-cell answer to upper and 

 lower surfaces of the leaf. The dehiscence is, it is true, apparently almost quite mar- 

 ginal, while in Trillidium G-oveniammn it is distinctly extrorse ; but here I find no difii- 

 culty further than may be explained by a slight dilatation of the inner face of the con- 

 nective, or by the development of the lobes answering morphologically to the inner pair of 

 thickenings of parenchyma upon the outer, or lower, face of the metamorphosed lamina, 

 instead of upon the inner or upper surface. In Smilax it would seem probable that the 

 anther-cells originate from but two thickenings of parenchyma, one on each side of the 

 midrib of the stamen-leaf. Dehiscence is along this median line, on the face of the anther 

 {vide PI. XLIV. fig. 18). I consider, indeed, the structure of the anthers in Paris to be 

 as easily explicable as in Geranium itself; in fact, the anthers in the latter present, from 

 their versatile attachment and inconspicuous connective, the more specialized structure 

 of the two. And it is from this circumstance especially that I think the evidence which 

 they afford on the question of anther-morphology to be important, since in Papaver, 

 Nyniph(Ba, and some other genera, in which the anther-cells have been observed to originate 

 upon the upper surface of a petaloid lamina, the anthers are innate or adnate, and the 

 connective sometimes quite conspicuous. And further, as Neumann {I. c, p. 358) I'e- 

 marks, the anther- sutures of Geranium present the dark line which Roeper noted in some 

 Euphorbiacese, and which he considered to be confirmatory of his view, that the suture 

 corresponded to the leaf- margin. Robert Brown, in his paper on Rafflesiat, in discuss- 

 ing the structure of anthers generally, says, in a note, " . . . . the principal point in which 

 the antherse and ovaria agree consists in their essential parts (namely, the pollen and 

 ovula) being produced in the margins of the modified leaf." But though the exterior, 

 or upper, anther-lobes originate as thickenings of the parenchyma, parallel and coinci- 

 dent, or nearly so, with the margin of the leaf, the inner and lower lobes have no such 

 necessary marginal relation. With regard to the origin of anthers from portions of tissue 

 morphologically corresponding to the outer lobes only, or inner lobes only, of the antlier- 



* It is true that the upper pair of anther-cells (in Cinnamomum at least) have their bases slightly included between 

 the upper points of the lower cells, and that the portions of the stamen-leaf thickened, in their case, cannot precisely 

 correspond in position with those prevailing in the abnormal forms which I figure ; but this I believe to be quite unim- 

 portant. In Berberideee (Be?be>-is, Epimedium, Leontice, Bonyardia), besides dehiscence along the line of junction 

 of the posterior and anterior lobes, the walls of the former separate round their base and, dorsally, along each side 

 the connective. The inner margins of the anterior cells remain attached, as is usual. The chambered anthers of 

 Viseum, jSfficeras, and some species of Rhi^ophora, the pore-dehiscence of several groups, distractile, appendaged, and 

 "one-celled" anthers, the anthers of Coniferee and Cycadese, do not offer for explanation greater difficulties on this 

 theory than on that of Cassini, Roeper, and others; indeed some, I think, are clearly more easily explicable on this view. 



t The amount of depression of the line of suture previous to dehiscence may vary shghtly in the species. In P. 

 hexaphylla I have seen it scarcely perceptible, excepting towards the extremities of the lobes ; but this was in a dried 

 specimen. In P. incom-pleta the connective is scarcely produced, as is often the case in P. polyphylla. Conf. Hooker, 

 111. Ilimal. Plants, pi. xxix. 



X Linn. Trans, xiii. 211. 



