1894 THE MICROSCOPE. 83 



in our food, bacteria live, feed and thrive, and thus we 

 are unable to avoid them. 



The work of the bacteriologist consists in gathering- 

 full evidence in regard to the specific organism connected 

 with a certain disease. In the first stages of many dis- 

 eases — such as pneumonia and tuberculosis, it is -of im- 

 portance to know whether a typical bacterium of the fatal 

 disease is present or not, and in what quantity. This 

 cannot be determined with full evidence by the patho- 

 logic diagnosis alone ; when it is united with the bacteri- 

 ological investigation, certainty may be reached, as suffic- 

 ient morphological, physiological, and biological char- 

 acters of many of the typical forms are known in detail, 

 so that comparing is possible. As the disease proceeds, 

 it is often necessary to follow the development of the 

 case. Therefore, the bacteriologist should work hand 

 in hand with the physician. 



Bacteriological investigations of air and water in towns 

 or smaller localities (wells, sewers, etc.,) are important, 

 and should be carried out at regular intervals so that 

 the danger of contamination may always be checked. A 

 great number of pathogenic forms will keep alive or actu- 

 ally live in water for a long time ; they will come into the 

 wells from the rottening or otherwise contaminated sub- 

 stances in the ground, etc., and attack the organism 

 either by direct introduction into the body or be trans- 

 mitted through the air from the surface of the water- 

 It is always important to have an estimate of the bac- 

 teria living or able to develop in the water from which 

 we are supplied. 



Of almost equal importance are researches on bacteria 

 in the atmosphere. The latter is in very many cases the 

 way of transmission, and important results have been 

 derived from such investigations. 



Bacteriological analyses of the ground in certain dis- 

 tricts are of importance in and after epidemics ; such 



