TRANSACTIONS OF SECTION D. — DEPT. ZOOLOGY AND BOTANY. 569 



9. On the Inflorescence of Senebiera didyma. By Alexander Dickson, M.D., 

 Begins Professor of Botany in the University of Glasgow. 



The inflorescence here, like that of the mass of Cruciferous plants, is racemose. 

 The racemes are " oppositifoliar," and at first sight the arrangement seems to he 

 analogous to that of the oppositifoliar inflorescences of Vitis or of Alchemilla 

 arvensis, where the inflorescence is really terminal, hut is thrown to the side hy a 

 preponderant development of a " usurping shoot," the axillary hud of the last leaf 

 produced hy the primary axis before ending in the inflorescence ; and it is to be 

 noted that, of all the foliage leaves, that opposite the raceme is the only one ap- 

 parently destitute of an axillary bud, which on the supposition would be represented 

 by the " usurping shoot." If, however, the plant is more closely examined, a very 

 remarkable condition is disclosed — one, indeed, which offers a morphological pro- 

 blem of considerable difficulty, and which probably can be effectually solved only by 

 developmental study. The peculiarity consists in the constant occurrence of a 

 solitary flower springing somewhere from the internode below the raceme, either 

 about half-way down towards, or almost close to, the level of the leaf below. So 

 far as observed, the solitary flower is never quite so low as the level of the lower 

 leaf. Probably the first idea which would occur to one would be that this is a 

 peculiar case of adhesion of parts ; it might be supposed that from almost imme- 

 diately above the second last leaf of the main axis, the bases of the terminal raceme, 

 of the " usurping shoot," and of the axillantleaf of that shoot, had all become fused 

 together. Now, although cases are known, on the one hand, of adhesion between 

 the base of a terminal flower and that of the " usurping shoot" {e.g., Helianthemum 

 vulgare), and on the other hand between the base of auaxillant leaf and that of the 

 usurping shoot in its axil (e.g., Sedum sp.), we do not know of connation of all three 

 together. It is possible, but not probable. The view which seems to the author 

 most fully to satisfy the conditions of this remarkable case may be stated briefly 

 in categorical form as follows:— 



1st. The racemose inflorescence is terminal, and properly begins just above the 

 level of the " second-last " leaf. It would thus include the aforesaid solitary flower. 



2nd. The raceme, after producing one ebracteate flower, produces at its second 

 node a foliage-leaf, from whose axil the "usurping shoot" springs. 



By such an explanation we can dispense with any cumbrous adhesion-hypothesis 

 such as that indicated above. The peculiarity is that the main axis does not per 

 solium pass from the condition of a leafy axis to that of an axis of inflorescence, 

 but begins by producing one flower and then developing a foliage-leaf, beyond which 

 the series of flowers is uninterrupted. The " usurping shoot," as above indicated, 

 represents the axillary bud of the foliage-leaf by which the raceme is interrupted. 



10. On the Six-celled Glands of Oephalotus, and their similarity to the Glands 

 of Sarracenia purpurea. By Alexander Dickson, M.D., Begins Pro. 

 fessor of Botany in the University of Glasgow. 



The author pointed out that the peculiar six-celled glands found on the outer 

 surface of the pitcher, both surfaces of the pitcher-lid, and both surfaces of the 

 foliage-leaf of Cephalotus, are very nearly identical iu structure with the glands on 

 both inner and outer surfaces of the pitcher of Sarracenia purpurea, which were 

 originally described by August Vogl. The author suggested that the remarkable 

 resemblance in this respect, taken in connection with certain correspondences in the 

 details of the insect-trapping apparatus, might indicate an affinity not hitherto sus- 

 pected. 



