311 



markings which are met with on their surface after the graius 

 have collapsed by the discharge of their contents. 



In regard to the mounting of these objects for the microscope, 

 they show to the best advantage when put up perfectly 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 fovilla is apt to con- 

 dense on the covering 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 occasionally 

 helpful in making out structure ; thus the pores of Campanula 

 rotundifoUa, 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 at the meeting. 



Microscopical and Natubal History Section. 

 Decemher 6th, 1869. 



JouN Watson, Esq., President of the Section, in the Chair. 



Mr. W. Boyd Dawkins, M.A., F.E.S., was elected a member of 

 the Section. 



Mr. Charles Bailey read a paper '' On Pollen, considered as an 

 Aid in the Differentiation of Species." [This paper was after- 

 wards read at the Ordinary Meeting of the Society, held Decem- 

 ber 28th, 18G9. See page 309.] 



Mr. J. B. Dancer, T.R.A.S., read a short paper on some of the 

 new Hydro-Carbon compounds from which he had obtained very 

 beautiful polarising objects for the microscope. These were 

 exhibited to the members, and a more detailed account promised 

 when the experiments are complete. 



