128 PRACTICAL BACTERIOLOGY. 



the cultivation of which sufficient has been said in 

 preceding chapters. But since, as was mentioned 

 before, various different species are present in the 

 hay infusion, which are all classed together under the 

 common name of hay bacillus, it is better to take up 

 with the loop of platinum wire a minute quantity of 

 the powdery sediment, which after a time settles at 

 the bottom of the vessel, and which consists of hay- 

 bacillus spores, and to make plate cultivations with it. 

 It is best to prepare three attenuations with this 

 materia], as very frequently so many spores adhere 

 to the platinum wire, and hence so many colonies de- 

 velop on the two first plates, that it is impossible to 

 obtain material for a pure culture from either of them. 



A number of slides in which depressions have been 

 ground, together with suitable cover- glasses, are then 

 sterilised. A drop of nutrient bouillon is placed on 

 one of the cover-glasses, and is inoculated with a small 

 quantity of one of the colonies from the cultivation 

 plate. The cover-glass is then turned over, placed on 

 the slide, and sealed up with vaseline or paraffin oil. 

 It is now best to put the slide into an incubator, 

 which is regulated to a temperature of about 24° C. 



At first the bacilli form long threads, which, being 

 confined by the narrow space, turn and twist about, 

 and become broken, so that sometimes their charac- 

 teristic formation is not easily seen. After a time the 

 nutrient material is exhausted, and they commence to 



