ZOOLOGY AND BOTANY MICROSCOPY, ETC. 301 



ordinary plates. Colour-photography on Luuiiere autochrome plates. 

 Spectographic photography. (Pages 455-58.) 



VI. Applications of the Luminescence Microscope. — Physics and 

 chemistry. Luminescence spectra of very small objects. Identification of 

 traces of mixtures. Mineralogy ; luminescence of thin slices. Botany ; 

 examination of thin sections, colour-stuffs, liquors. Biology ; examina- 

 tion of living inferior creatures. (Pages 458-70.) 



(2) Eye-pieces and Objectives. 



Zeiss' New Homogeneous Immersion 1/7.* — The firm of Carl Zeiss 

 has recently introduced a one-seventh oil-immersion objective. This 

 objective has a working distance of 0*35 mm., its focal length is 

 3 • 5 mm. and the N. A. is ' 9. It may be used with either Huyghenian 

 or with compensating eye-pieces, giving with the latter a more colour- 

 less image, more noticeable towards the margin of the field. Though 

 this novelty is of quite recent production, the idea of making homo- 

 geneous immersions of small aperture was first entertained by Abbe 

 many years ago. The advantages claimed by the makers are that there 

 is less trouble than is the case when examining a specimen with a dry 

 medium power and then changing to an oil-immersion ; secondly, there 

 is more perfect correction of spherical aberration ; and thirdly, that the 

 correction of the objective is far less sensitive to variations in the thick- 

 ness of cover-glass and of the embedding material. 



Healy's Comparison Ocular.f — D. J. Healy suggested to Mr. 

 Bausch in January 1912, the convenience of equipping a Microscope 

 with two objectives, so that on looking through the eye-piece one would 

 see half of the field of each objective. The Bausch and Lomb Optica] 

 Co., however, ultimately developed the idea into the use of two identical 

 Microscopes placed side by side. After removing the draw tubes the 

 collars of the body tubes were replaced and a comparison ocular attached 

 by fitting a short tube snugly into the body tube of the left-hand instru- 

 ment, and another short tube loosely into the right-hand body tube. 

 The comparison ocular itself consisted of a set of reflecting prisms 

 within a horizontal box carrying a vertical eye-piece. The author 

 claims that his instrument does not require a specially constructed 

 Microscope, and that it is quite satisfactory in operation. He gives 

 several microphotographs showing comparison fields. 



(3) Illuminating and other Apparatus. 



New Electrical Heating Apparatus applicable to any Micro- 

 scope. J — R- Brandt refers to the demand that the progress of micro- 

 crystallography and of microchemistry have raised for instruments with 

 heating stages. As it is not easy to adapt such stages, as have hitherto 

 been designed, to ordinary Microscopes, special instruments are usually 



* Carl. Zeiss Special Catalogue, 1914. 



t Journ. Amer. Med. Assoc, lxi. (1913) pp. 1958-9 (6 figs.). 



% Zeitschr. wiss. Mikrosk., xxx. (1914) pp. 479-84 (1 fig.). 



