78 PRACTICAL BACTERIOLOGY. 



on account of its simplicity^ for the further cultivation 

 of strictly anaerobic hacteriaj and we can invariably 

 make use of it for this purpose. 



If it is wished to take specimens of bacteria from 

 these cultures for microscopical examination, or, 

 above all, for staining, all sorts of difficulties present 

 themselves, amongst which the two most important 

 are the following. Either too little of the colony 

 adheres to the loop of platinum wire, the rest having 

 been rubbed off the wire by the upper part of the 

 nutrient medium as it was taken out, or so much is 

 obtained that the difficulty of spreading the bacteria 

 out on the cover-glass and ot staining them later on 

 is much increased, whilst the cleanliness and clearness 

 of the preparation is much injured. 



This difficulty can be overcome, in at any rate the 

 majority of cases, in the following manner. Test-tubes 

 which are filled for about one-third of their length, 

 as a rule, with gelatine or agar-agar, are boiled for a 

 few minutes in order to expel the air as much as 

 possible, and are then laid in a slanting position in 

 iced water in order that ' their contents may solidify 

 quickly before much air can get in again. The con- 

 densation water, in the case of the agar-agar, is then 

 allowed to run out; the medium is quickly inoculated, 

 the material being rubbed over it as gently as possible 

 so as not to disturb its surface, and the test-tube is 

 inverted and placed over a tube which is bent at right 



