CHAPTER I 



MICROSCOPIC EXAMINATION 



For the examination of micro-organisms good high powers 

 are essential, at the least a power magnifying 300 to 400 

 linear diameters. Zeiss' D or E and Zeiss' or Leitz's or 

 Reichert's oil immersion i-i2th or i-i6th inch (2 mm.) will 

 be found sufficient for all purposes. In the case of tissues 

 stained with aniline dyes a good substage-condenser such as 

 Abbe's or Powell and Lealand's, is invaluable. I use Zeiss' 

 or Leitz's stand with Abbd's condenser, open diaphragm, 

 and plane mirror. As Koch 1 pointed out, and what is now 

 universally acted upon, stained specimens mounted in 

 Canada-balsam solution or Dammar varnish, when exa- 

 mined over an Abba's condenser, show the micro-organisms 

 with e.xtreme clearness and sharpness. 



The examination of the morphological characters of an 

 organism is carried out on fresh unstained, as well as on 

 fresh stained, microscopic specimens. Although the latter 

 method is, for reasons hereafter to be mentioned, by far the 

 most perfect and reliable one, it is nevertheless important to 



^ Die Aeiiologie d. Wimdinfectionskranhheitcn, p. 34, Leipzig, 1879. 

 Translated as Trauviatic Infective Diseases (New Syd. Soc), London, 

 1880. 



