Societies and Academies

Abstract

LONDON. Royal Microscopical Society, March 16.—Prof. John Eyre, president, in the chair.—J. H. Pledge: The use of light-filters in microscopy. The advantages gained are: control of contrast in the stained and the coloured preparations from both the visual and the photographic points of view; aid in resolution of fine structure; improvement in the definition given by ordinary achromatic objectives; modification of the unpleasantness to the eye of artificial-light sources by “equivalent daylight” filters; and the possibility of moderating the intensity of illumination of the microscopic field by light-filters of neutral tint of suitable density. Forms of light-filters mostly in use are chiefly dyed gelatine cemented between protecting cover-glasses, but dye solutions in glass-cells are also used. To obtain maximum contrast a light-filter complementary in colour to that of the preparation should be used.