CHAPTEE III. 



METHODS OF BACTEEIOLOGICAL STUDY- 

 STAINING, ETC. 



The study of micro-organisms by means of pure cultures — Gelatine 

 plate cultures — Esmarch roll cultures — Streak, stab and shake 

 cultures — Culture of anaerobic bacteria — Hanging-drop cultures — 

 Permanent cultures — Indol reaction — Methods of staining and 

 mounting bacteria, their spores and flageUa — The imbedding and 

 cutting of sections of tissues — The staining of micro-organisms in 

 sections. 



Foe the study of the growth of the bacteria, various 

 materials, both liquid and solid, have already been described 

 in the previous pages. The introduction of solid media by 

 Koch in 1881 inaugurated a new era in the progress of our 

 knowledge relating to the bacteria. It was observed by 

 Koch that when a slice of cooked potato was exposed to the 

 air, and afterwards kept moist and at a suitable tempera- 

 ture in a covered chamber, small isolated dots and patches 

 made their appearance after a few days. The various 

 centres or colonies may present very different characters 

 both in shape and colour. It was found that each of 

 these points was made up of micrococci and bacilli, and in 

 nearly every case a pure cultivation or colony of a par- 

 ticular organism. Each individual organism which gained 

 access to the potato was fixed in situ, and, being unable 

 to move from the spot, commenced to grow, and in a short 



