CHAPTER II. 



BIOLOGY OF BACTEEIA. 



Distribution : When beginning the study of bacteriology the 

 student is rather inclined to scoff at the statement that bac- 

 teria can be found everywhere. This skepticism frequently 

 breeds carelessness on his part, necessitating much extra work. 

 It is well, therefore, to begin one's study with the firm convic- 

 tion that, no matter how careful he is, it is still possible for 

 contamination to occur. Bacteriologic technique is tedious and 

 time is precious, hence the student will do well to "make 

 haste slowly ". The cultivation at this time of habits of 

 carefulness, thoroughness, and cleanliness will save him much 

 worry and many sleepless nights in later life, when he may 

 have ample opportunity to observe and become cognizant of 

 the ever-present bacteria. 



Bacteria are found in the air, in water, in the ground, and 

 in all kinds of food and drink. The surface of the body 

 invites the lodgement of both pathogenic and non-pathogenic 

 bacteria, and some varieties even penetrate the protecting 

 surface epithelium. This is of importance to the surgeon, 

 and enforces the oft-repeated admonition of the bacteriologist, 

 that the hands of the operator should receive most careful 

 attention prior to an operation in order to assure even a modi- 

 cum of safety and freedom from infection of fresh wounds. 

 The various cavities which lead into and out of the body also 

 contain a diversified flora. Under normal conditions the 

 body-juices and -tissues are entirely free from bacteria. By 

 means of cultures it can readily be demonstrated that the 

 walls and floors of rooms, and especially hospital wards, are 

 never free from bacteria. Fortunately most of them are not 

 pathogenic organisms. It is well for us all constantly to bear 

 in mind this universality of bacteria. It will account for the 



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