568 report— 1878. 



6. Notes on some Dimorphic Plants. By Alex. S. Wilson, M.A., B.Sc. 



This paper had reference to Erythrma centaurium and Silene acaulis. The 

 author pointed out that the former plant was probably dimorphic, as it exhibited 

 heterostyly and had two kinds of pollen grains, in these respects closely resembling 

 the primrose and bog-bean, as well as several others belonging to the order Gen- 

 tianacece, of which it is a member. Silene acaulis was shown to have three kinds of 

 flowers, male, female, and hermaphrodite, thus resembling S. inflata, which Axel 

 has shown to be trioeciously polygamous. 



7. Some Mechanical Arrangements subserving Cross-fertilisation of Plants 

 by Insects. By Alex. S. Wilson, M.A., B.Sc. 



The plants considered were Pinguicula vulgaris, Vinca minor, and the fox-glove. 

 In Vinca the curiously shaped stigma resembles the stopper of a glass bottle. The 

 circumference of its lower disc secretes a viscid substance which serves to smear the 

 pollen so as to cause it to adhere to insects, thus resembling physiologically the 

 sticky disc of the common orchid. The filaments of the stamens present a curious 

 geniculate bend close to their insertion on the corolla, which acts as a lever when 

 depressed, lowering the anther with its pollen into contact with the viscid matter 

 on the lower part of the stigma. Somewhat similarly a peculiar bend on the fila- 

 ments of the two stamens of Pinguicula, when pressed, causes the anthers to descend 

 so as to impinge on an insect entering the flower, this latch-like mechanism dislodging 

 the pollen from behind the under lip of the semi-petaloid stigma. The remarkable 

 twists and curvings of the filaments of the fox-glove appear to act in a manner 

 exactly analogous, for an insect pressing on their upturned edges as it passes over 

 the floor of the flower must cause a shower of pollen to fall on its back from the 

 overhanging anthers, on account of the disturbance produced by this lever-like 

 mechanism. 



8. On the Stipules of Spergularia Marina. By Alexander Dickson, M.B., 

 Regius Professor of Botany in the University of Glasgow. 



The stipules of this plant exhibit a peculiarity, which, if observed at all by de- 

 scriptive botanists, has not received the attention it deserves on account of its re- 

 markable character. The stipules are free from the petioles, and are wholly 

 cellular in structure. From connation of those of opposite leaves they form " in- 

 terpetiolar stipules," with more or less regularly, though slightly, bifid extremities. 

 Lastly (and this is the important point), these stipules are united to each other 

 round the backs of the petioles, so that a sheath is formed completely surrounding 

 the axis and the two leaf-bases. This connation of stipules round the backs of the 

 petioles is very interesting, as being a rare phenomenon. Cases are not uncommon 

 where the two stipules are connate on the inner side of the leaf-base, constituting 

 the so-called " axillary stipule," e.g., Potamogeton lucens, &c, or on the opposite 

 side of the axis from the leaf, e.g., Ficus elastica, Ricinus, Astragalus alpinus, &c, 

 constituting the so-called " oppositifoliar stipule ; " but the only reference to conna- 

 tion of stipules behind or outside the leaf-base the author has been able to find, is to 

 the case of certain species of Astragalus by St. Hilaire in his ' Morphologic' In 

 those species of Astragalus examined by the author he did not meet with any 

 where the stipules are actually connate in this way ; but in some, e.g., A. alopecuroides, 

 the bases of the stipules extend round the back of the leaf-stalk till they meet — a 

 condition just short of connation. In the stipules of S])ergularia, as we have seen, 

 there is the interesting combination of the interpetiolar connation, with connation 

 round the back of the leaf. In " English Botany " the condition is fairly enough 

 represented by the artist, but the morphological peculiarity does not hitherto seem 

 to have impressed itself upon the botanical mind. 



