STUDIES ON AEROBIC SPORE-BEARING NON-PATHO- 

 GENICi BACTERIA 



Part I 



From the Laboratory of Hygiene and Bacteriology, Johns Hopkins University 



INTRODUCTION 



BY W. W. FORD 



One of the most important problems of modern hygiene is libkarv 

 the identification and classification of the bacteria in our environ- new yOk.x 

 ment. Microorganisms of various kinds exist everywhere in fiv"f *.s\r. * • 

 nature and influence profoundly all sorts of substances which o av, . 

 affect man's physical condition. This is true of food-stuffs in 

 general and especially true of milk which is markedly altered in 

 its chemical composition by the bacteria which multiply in it. 

 The microorganisms in our environment are of various sorts, 

 pigmented bacteria, spore-bearing bacteria, yeasts, moulds, 

 etc. Some of these forms are identified without great difficulty 

 but our knowledge of the spore-bearing bacteria is still in a 

 state of chaos. The reason for this lack of knowledge is not far 

 to seek. The science of bacteriology developed primarily among 

 physicians whose interest naturally lay in the disease-producing 

 properties of the various parasites which infect man and the 

 animals. Non-pathogenic bacteria were of importance chiefly 

 as laboratory contaminations to be avoided. With the de- 

 velopment of industrial bacteriology those species were again 

 most carefully studied which seemed to serve some distinct 

 purpose in nature, as for example, the nitrifying bacteria of the 



' The term "non-pathogenic" is used here in the sense of "lacking in disease- 

 producing properties." Many spore-bearing bacteria are at times pathogenic 

 to small animals and instances are reported in which they may produce inflam- 

 matory reactions when vegetating on mucous surfaces. The organisms here 

 described are however in no instances capable of producing definite diseases 



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