1 8 BACTERIOLOGY. 



and Swift & Son of London, may all be recom- 

 mended for constructing an arrangement in which 

 the photographic camera is combined with the 

 microscope. 



For illumination either sunlight or artificial light 

 may be employed. In the case of sunlight a helio- 

 stat is necessary to procure the best results, but as 

 sunlight is not always available by day, and it is 

 also more convenient for many to work at night, it 

 is better to have recourse altogether to artificial 

 light. Excellent results may be obtained with an 

 ordinary paraffine lamp, or with magnesium, oxycal- 

 cium, or electric light. Specimens are preferably 

 stained yellow, brown, or black, and for mounting 

 the preparations Koch* recommends a saturated 

 solution of acetate of potash ; but there is little or 

 no objection to the use of Canada balsam dissolved 

 in xylol. Hauser,f who employed the electric light, 

 obtained some excellent pictures of preparations 

 mounted in balsam. Van Ermengem* first recom- 

 mended the isochromatic dry plates, and produced 

 most successful results with the lime-light from 

 objects stained with fuchsine and methyl-violet. 

 The author also has investigated the applicability 

 of photographic processes for illustrating micro- 



* Koch, Verfahren zur Untersuchung zum Conserviren und 

 Photographiren der Bacterien . 1877. 



t Hauser, Uber Faulniss Bacterien und deren Bcziehungen zur 

 Septicdmie. 1885. 



\ Van Ermengem, Bull, de la Soc. Beige de Microscopic, No. X., 

 pp. 170-2. 1884. 



