PHYSICS AND NATURAL HISTORY OF GENEVA. 297 



destitute of a calyx, and taking account of the arrangement of the flower in 

 the species Dactylostemon and ActinOf?temon, M. ^luller arrives at the conception 

 that the part (situated above the articulation of the male flowers of the Euphor- 

 bias should be regarded as an axis — that is to say, as a part of the articulated 

 pedicle destitute of a calyx, or rather a prolongation of the receptacle bearing 

 on its summit a sessile anther. There would then be nothing herein very 

 paradoxical, and we should only have a monandrous flower, the filament of 

 which would be as large as and sometimes larger than the pedicle. The same 

 member announced (December 21, 1865) that in the genus Macaranga of the 

 family of the EuphorbiaceiB he has met with individuals, which presented on the 

 same flower stamens with three and with four loculaments. This would suppress 

 the genus Pachystemon, which would no longer be distinguished by any char- 

 acter from the genus Macaranga. 



In the last place, M. Muller (May 3, 1866) spoke of the secondary characters 

 (f the aestivation of the ca^yx, which enable us, even long after ihe expansion of 

 the flower, to recognize in what manner the lobes of the calyx or the sepals must 

 have been disposed at the time of the budding. In tlie valvate aestivation, these 

 lobes or sepals are all equidistant from the arch of the flower, and, before the 

 expansion of the calyx, each lobe from the base to the summit touches its neigh- 

 bor by the unattenuated edge of its borders. In the imbricated aestivation, on 

 the contrary, the lobes are not equidistant from the centre, one of the two neigh- 

 boring lobes being always more exterior than the other, and one of the borders 

 covering the other. In the first case, the lobes are necessarily acuminated in 

 order to their meeting at the summit of the calyx, and (if the calyx be straight) 

 they have necessarily the same length, and the borders, touching one another 

 face to face in the same plane, cannot but be entire. Hence M. Muller considers 

 it est iblished that, in flowers which have already opened, each of the five follow- 

 ing characters indicates an imbricated aestivation in the bad : 



1. Sepals, or lobes of the calyx, being alternately of an equal length, 



2. Sepals, or lobes of the calyx, being rounded at the summit. 



3. Sepals, or lobes of the calyx, being attenuate, membranous or scabrous on 

 their borders. 



4 Sepals, or lobes of the calyx, being variously dentated, lobated, laciniated, 

 or otherwise divided. 



5. Sepals, or lobes of the calyx, having marginal (particular) bristles, situated 

 in the same plane with the lobes. 



M. Casimir de Candolle communicated to the society (January 4, 1866) a 

 memoir on the Jamily of the Piperacece, which is to form part of the Prodromus. 

 The author divides the family into two groups, the Piperomise and the Piperise, 

 according to the organization of the stalk. In treating of the evolution of the 

 leaves, and of their structure, he establishes that the so-termed stipules opposed 

 to the leaves are prophylla; that the mode of evolution of the buds and the 

 arrangement of the leaves explain the irregularity of the limbs. As to the 

 nervation, it is in this family penninervate or digitinervate ; but these two sys- 

 tems enter into the same type in the same manner as the intermediate nervations 

 called multiplinervate. If, in efiect, sections be made in the leaf at different 

 distances from the petiole, the lateral nervures are seen to proceed from the 

 median nervure, and all the nervures are formed of the prolongation of the ex- 

 ternal layers of the peripheral fasciculi of the boughs. On comparing the disti i- 

 bution of the fasciculi in the bough and the leaf, certain analogies are perceived be- 

 tween these two organs, which are commonly considered as very different. Tiie 

 leaf offers analogues of the bark, of the ligneous system, and the medulla ; it often 

 represents a flattened bough. The author concludes with a table of the classifi- 

 cation, in which he materially reduces the number of species admitted oy some 

 botanists. 



M. Edmond Boissier exhibited February 1, 1866) specimens of three kinds 



