52 PROCEEDINGS OF SOCIETIES. 



shallow to admit of no more than a single layer, and, at the same time, deep 

 enougli to permit tlie grains to move about. If pollen is mounted soon after 

 it lias been discharged from the fresli anthers, the fovilla is apt to condense on 

 tlie covering glass, and the slide soon becomes useless. The stamens taken 

 from an unojiened flower-bud furnish the best and cleanest pollen, and these 

 should be selected in preference to tliose taken from the fully developed flower. 

 Canada balsam, glycerine, and other media, are occasionally helpful in making 

 out structure ; tlius the pores of Campanula i-otundifolia, Phyteuma Halleri, 

 and other allied species, are made much more distinct when mounted in balsam. 

 A large series of slides illustrative of the above remarks was exhibited. 



Edinburgh Botanical Society.— The first meeting of the thirty-fourth 

 Session of the Society was held on Thursday, 11th of November, at 5, St. 

 Andrew Square ; Dr. Cleghorn, President, in the chair. Professor Balfour 

 referred to the great loss which the Society had sustained since theu' last 

 meeting, by the death of William Brand, Esq., W.S., their auditor. The 

 President delivered an opening address on the " Progress and State of Botany 

 in Britain," which we hope to give in extenso. On the motion of Professor 

 Balfour, a vote of thanks was cordially given to Dr. Cleghorn for his address. 

 The following communications were read: — I. On Equations to the Curved 

 Outlines of the Leaves of Plants. By Mr. William Mitchell. The author 

 stated that, some time ago, he read a paper before the Society, in which he 

 suggested a method of approximating the mean curves of leaves of plants, 

 intending to follow it up by a series of measurements. During last summer 

 he had resumed the subject, taking, however, the true outline instead of the 

 mean curve. All he proposed was, to find formulas to express the curves of the 

 outlines, so closely that the calculated values should not differ from those 

 measured more than the proportional measurements of several leaves of the 

 same plant differ among themselves, by reason of their ordinary variations. 

 His mode of procedure was as follows : — " Selecting a characteristic and well- 

 developed leaf of any plant, I carefully trace its outline when placed on card- 

 board or stout paper ; but when both sides appear to be equally developed, 

 one-half the outline is sufficient. On this copy all the measurements are made. 

 The point corresponding to the base of the midrib of the Feaf is fixed on for 

 tlie pole, or origin of measurement, and from it lines are drawn to the outline, 

 making equal angles with each other. These lines are then measured by a scale 

 divided on the edge into tenths of an inch ; and as the first line, or radius 

 vector, is the longest, we have a descending series of terms from which to con- 

 struct a formula for the curve in question." II. Supplementary Notes on the 

 Lichen Flora of Greenland. By W. Lauder Lindsay, M.D., F.L.S., F.R.S.E. 

 This paper was supplemental to a former one by Dr. Lindsay, published in the 

 Society's Transactions, vol. x. (1869) p. 32, and consisted chiefly of a com- 

 mentary on a list of Greenland lichens, by the Chevalier Charles Louis 

 Giesecke, in Brewster's ' Edinburgh Encyclopa;dia,' vol. x. (1830) pp. 495-6, 

 the existence of which the author was ignorant of when the former paper was 

 published. Giesecke's list comprehended only fifty-seven species, while the 



