26 Dairy Bacteriology. 



bacteriology, as it is the only way in which it is possible 

 to secure a quantity of germs in a pure state. 



The microscope in bacterial investigations. In order 

 to verify the purity of the cultures, the microscope is in 

 constant demand throughout all the different stages of 

 the isolating process. For this purpose it is essential 

 that the instrument used shall be one of high magnify- 

 ing powers (600 to 800 diameters), combined with sharp 

 definition. 



The microscopical examination of any germ is quite 

 as essential as the determination of culture character- 

 istics, in fact, the two must go hand in hand. The ex- 

 amination reveals not only the form and size of the in- 

 dividual germs but the manner in which they are united 

 with each other, PS well as any peculiarities of movement 

 that they may possess. 



In carrying out the microscopical part of the work, 

 not only is the organism examined in a living condition, 

 but colored preparations are made by using solutions of 

 anilin dyes as staining agents. These are of great serv- 

 ice in bringing out almost impreceptible differences. 

 The art of staining has been carried to the highest de- 

 gree of perfection in bacteriology, especially in the de- 

 tection of germs that are found in diseased tissues in the 

 animal or human body. 



In studying the peculiarities of any special organism, 

 not only is it necessary that these cultural and micro- 

 scopical characters should be closely observed, but spe- 

 cial experiments must be made in different ways, in 

 order to determine any special properties that the germ 

 may possess. Thus, the ability of any form to act as a 

 fermentative organism can be tested by fermentation 

 experiments; the property of causing disease, studied 



