CHAPTER IV. 



METHODS OF STUDYING MICROORGANISMS 

 -STERILIZATION BY HEAT. 



LABORATORY TECHNIC. 



IN the study of microscopic beings it has been 

 necessary to elaborate a special technic which will 

 supply the requirements of life. Before the epoch- 

 making work of Koch it was necessary to cultivate 

 microorganisms upon broth or bread, and there was 

 little known as to the exact composition of the medium. 

 Koch showed how to control the growth of bacteria 

 in the laboratory. To Pasteur and Kohn credit also 

 is due for the standardizing of the foodstuffs upon 

 which bacteria are cultivated. Let us assume that we 

 have been given a culture of bacteria to study. Since 

 the identification of species is not a part of a nurse's 

 duty it is not necessary to discuss the separation of 

 many germs in a mixture. Bacteria are transferred 

 from one place to another, as, for example, from one 

 culture tube to another or to a glass slide, by means of 

 a piece of platinum wire set into a handle. This metal 

 will withstand great heat and can be sterilized in the 

 flame of a Bunsen burner after every using. The 

 Bunsen burner is an apparatus so arranged that air 

 is thoroughly mixed with the gas and the mixture 

 is completely burned. Starting out with the material 



