1896.] 



MICROSCOPICAL JOURNAL. 



203 



the lantern in the same way, and when oil is employed a 

 tri-wick lamp with only the middle wick lighted is used 

 in the lantern. The large double condensers of the lan- 

 tern serve to concentrate the light, while the double 

 lantern body prevents the radiation of heat to the micros- 

 cope and shuts off all radiating light. These are great 

 advantages, for not only is the illumination improved by 

 the concentration of light but the microscope does not 



Fig. 6. — Klebs-Loeffler bacillus, grown on blood serum, stained withLoeffler's 

 methyl blue, x 1,000 diameters. Exposed two minutes to oil light 

 with yellow-light filter, using Zeiss' two-millimetre apochromatic ob- 

 jective, projection ocular No. 4, and Abbe condenser in substage. 



By courtesy of Medical Record. 



become heated, and if the room can be darkened, as it 

 should be, by adjustable window shades, the absence of 

 extraneous light greatly facilitates focusing on the cam- 

 era screen. This method of using oil or gas light renders 

 them sufficiently powerful for practical purposes and with 

 acetylene gives great illuminating and actinic power. 

 With oil light used without a light filter, bacteria can be 

 photographed with amplifications of one thousand diam- 



