54 
In regard to the mounting of these objects for the micro- 
scope, they show to the best advantage when put up per- 
fectfy dry; the cells should be sufficiently shallow to 
admit of no more than a single layer, and at the same time 
deep enough to permit the grains to move about. If 
pollen is mounted soon after it has been discharged from 
the fresh anthers the fo villa is apt to condense on the cover- 
ing glass, and the slide soon becomes useless. The stamens 
taken from an unopened flower-bud furnish the best and 
cleanest pollen, and these should be selected in preference 
to those taken from the fully developed flower. 
Canada balsam, glycerine, and other media are occasion- 
ally helpful in making out structure ; thus the pores of 
Campanula rotundifolia, 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 
O 
was exhibited at the meeting. 
MICROSCOPICAL AND NATURAL HISTORY SECTION. 
December 6th, 1869. 
John Watson, Esq., President of the Section, in the 
Chair. 
Mr. W Boyd Dawkins, M.A., F.R.S., was elected a member 
of the Section. 
Mr. Charles Bailey read a paper “ On Pollen, consi- 
dered as an Aid in the Differentiation of Species.” [This 
paper was afterwards read at the Ordinary Meeting of the 
Society, held December 28th, 1869. See page 51.] 
Mr. J. B. Dancer, F.R.A.S., read a short paper on some of 
the new Hydro-Carbon compounds from which he had ob- 
tained very beautiful polarising objects for the microscope. 
These were exhibited to the members, and a more detailed 
account promised when the experiments are complete. 
