THE MICROSCOPE 63 



of the colony, using the terms on the descriptive chart 

 of the Society of American Bacteriologists, p. 134, as far 

 as possible. 



7. Compare the giant colonies of a Mucor, Pencillium, 

 a yeast and Bacillus subtilis or Bacillus mycoides. Use 

 agar for giant colonies of these bacteria, as they liquefy 

 gelatin. 



8. Giant colonies of yeasts and bacteria and some molds 

 may be grown in Petri dishes, or in flat-bottomed flasks. 



For illustrations of giant colonies of bacteria see: 



FUHRMAN: Vorlesungen iiber Technische Mykologie, pp. 41, 43. 

 LOHNIS: Vorlesungen iiber Landwirtschaftliche Bakteriologie, pp. 38, 



170. 

 LEHMANN AND NEUMANN: Bakteriologie und Bakteriologische Diag- 



nostik, Bd. I. (Atlas.) 



For illustrations of giant colonies of yeasts see: 



LAFAR: Technische Mykologie, Bd. 4, German Ed., pp. 24-25, 306, 

 and above references. 



THE MICROSCOPE 



Care of the Microscope. For microbiological work a 

 compound microscope is necessary. This should be fitted 

 with a minimum of two oculars corresponding to the Leitz 

 No. 1 (lowest power) (Spencer, 6X), and No. 3 or 4 (Spencer, 

 10 X) and three objectives corresponding to the Leitz 

 J in. (lowest power) (Spencer, 16 mm.), -f in. (Spencer, 4 

 mm.) objectives (dry) and ^ in. oil immersion objective. 

 A coarse and a fine adjustment permit the accurate focus- 

 ing of any combination of lenses. The substage shoi Id be 

 fitted with a good condenser and iris diaphragm for regulating 

 the amount of light, and a plane-concave mirror. 



Great care should be exercised in the use and care of the 

 microscope as it is a delicately adjusted instrument. 



The following rules should be heeded: 



The Stand. The stand is the body of the microscope 

 carrying the optical parts. 



