SYSTEMATIC AND DESCRIPTIVE. 



thick capsule of cartilaginous consistency. In a 

 solution containing acid tartrate of ammonia the 

 fungi generate butyric acid, and change the ori- 

 ginally acid fluid into an alkaline one. They were 

 first observed on putrid broth, and later on or- 

 dinary nourishing solutions ; they also readily 

 develop upon damp slices of boiled roots, carrots, 

 beetroots, etc. 



METHODS OF STAINING Cocci. 



Cocci stain well with watery solutions of gentian-violet, 

 methyl-violet, fuchsine, methylene blue, and bismarck 

 brown. For examining cocci in liquids such as pus or 

 blood, or in cultivations in solid media, a little of the 

 material should be spread out on a cover-glass [page 46], 

 and stained with a drop or two of a watery solution of 

 fuchsine or methyl-violet. The former is especially recom- 

 mended for staining Merismopedia gonorrhoea. 



For a zooglcea, or pellicle of micrococci Klein recom- 

 mends transference bodily to a watch-glass containing the 

 dye, leaving it there till deeply tinted, then taking it out 

 with a needle, washing in water, and then in alcohol till 

 excess of colour is removed. It must then be transferred 

 to a glass-slide, spread well out, and a drop of clove-oil 

 placed on it ; after a minute or two the clove-oil is drained 

 off, a drop of Canada balsam added, and covered with a 

 cover-glass.* 



Cocci in the tissues may be stained by immersing the 

 sections in an aqueous solution of gentian violet, or in 

 aniline-gentian-violet solution, then rinsing in water, de- 

 colorising in alcohol, treating with clove-oil, and preserving 

 in balsam (p. 55) ; or, after washing with alcohol they 



* Klein, Micro-organisms and Disease, 1885. 



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