THE MICROSCOPE

IN revising the matter for this, the seventeenth, edition of The Microscope changes have been made in every chapter in text and often in illustrations to render the subject more easily understood. Attention has been called to the newly devised Electron Microscope with its greatly increased magnifying power and resolution over the ordinary microscope to Polaroid for the micro-polariscope to some new plastics for mounting in place of Canada balsam to the high pressure mercury lamps for ultra-violet radiation and the bright mercury lines for photographing objects with the microscope. In general, however, the book retains its former character, and it is hoped that it will continue to serve students and users of the micro scope in understanding the underlying principles involved in micro scopical work. As a final word, I wish to express my thanks and appreciation for the new cuts loaned and other aid rendered by the American manu facturers, the Bausch Lomb Optical Company of Rochester and the Spencer Lens Company of Buffalo. The heads of those com panies, Edward Bausch and Harvey N. Ott, have been my friends and advisers for many years and have been ever ready to help me over the rough places in my microscopical career. Likewise it is a pleasure to render thanks to my University col leagues and to my fellow microscopists for their friendly interest and help also to Clara Starrett Gage, Ph. D. for aid in preparing illus trations, making corrections and revising the index for this edition. SIMON HENRY GAGE May 20, 1941. Contents include