58 PHARMACEUTICAL BACTERIOLOGY 



temperature ranging from o°C. to 20°C. are said to be cold loving (psych- 

 rophile), from io° to 4S°C., mesophile, from 40° to 70° C, thermophile. 

 Thermophile species are found in decaying vegetable matters, whereas 

 psychrophile species are found in cold water and cold soils. 



Bacterial life processes result in the formation of many substances, 

 some of which are of the greatest importance. It is impossible to estimate 

 properly the enormous tasks performed by these minute organisms, nor 

 shall we at this time make any attempt to set forth the great good and the 

 apparent great harm done by them. We need only state that without 

 rotting microbes soil formation, would be impossible, and without soil, 

 higher plant and animal life, as we now know them, would be implossible. 

 Without plant food digesting microbes crop growing would be impossible. 

 The saltpeter deposits in South America and the iron deposits of the Mesabi 

 range of Minnesota are said to be the result of bacterial action. We make 

 extensive practical use of microbes in medical practice, in the dairying 

 industry, etc. 



We will mention only a few substances of undoubted microbic origin. 

 Ptomaines and toxalbumins are well-known poisons elaborated by sapro- 

 phytic microbes which feed on meats and other organic substances, causing 

 the familiar putrefactive changes. Pahogenic microbes elaborate toxins 

 to which are due the manifestations of the disease. Acetic acid, lactic acid, 

 and butyric acid are elaborated by Bacillus aceticus, B. acidi lactici, and 

 B. butyricus, respectively. Some species liberate odoriferous substances, 

 others gases, coloring substances, phosphorescence, etc. The phosphores- 

 cence observed on the ocean is supposed to be due to bacteria {Bacillus 

 pkosphorescens indicus). Phosphorescent bacteria occur in dead fish and 

 in meat. Old cultures in animal nutrient media and in the presence of 

 sodium salts are phosphorescent in the dark, sufficiently so, to have sug- 

 gested making bacterial lamps and signal lights. 



It has been suggested that certain diseases, of which the causes are at 

 present unknown (as yellow fever, measles), maybe due to organisms so 

 small as to be invisible (ultra micro-organisms). It is known that the 

 virus of yellow fever will pass through the most compact clay or porcelain 

 filter. Attempts have been made to demonstrate the presence of ultra 

 micro-organisms by special photomicrographic methods, aided by special 

 illuminating devices (the ultra microscope of Siedentopf and Szigmondy) 

 but without success. Furthermore, no one has succeeded in culturing 

 such theoretically surmised organisms in artificial media, which would 

 certainly render them visible en masse. It may, however, be possible 

 that some ultra-organisms are obUgative parasites hence will not develop 

 in artificial media. 



The biological (symbiotic) relationship of different species of bacteria . 



