PART III. 



BACTERIOLOGY. 



Bacteriology deals with minute vegetable organisms known as 

 bacteria, microbes, germs, etc. The science is comparatively new, 

 and while it is suggested in some quarters that it has accomplished 

 naught of practical value except the discovery of the bacillus of 

 consumption, thereby emphasizing the importance of properly dis- 

 posing of tubercular sputum, yet this alone is adequate compensa- 

 tion for the labor thus far bestowed. But this is not all. The work- 

 ers in this field have discovered the specific cause of a number of 

 other diseases, the means of preventing the spread of these diseases, 

 and certain remedies of inestimable value such as the antitoxin for 

 diphtheria. The results of future investigations will probably ex- 

 ceed the hopes of the most sanguine. 



CHAPTER XXII. 

 CHARACTERISTICS AND CLASSIFICATION OF BACTERIA. 



Characteristics. Bacteria are unicellular, non-nucleated, vegeta- 

 ble organisms, which reproduce by normal fission and by endospores. 

 With but three exceptions, they are devoid of chlorophyl. They are 

 parasitic and saprophytic. Many infest the human body, some 

 producing infectious diseases, while others are supposed to aid in 

 the processes of digestion and assimilation. They assist in the de- 

 composition of dead organic substances, thus performing an inesti- 

 mable service to man. They reproduce by normal fission and the 

 formation of endospores. Normal fission is accomplished by the 

 division of the protoplasm and the formation of a partition between 

 the two halves. As the cells continue to multiply, they often co- 

 here, thus forming a filament. In other cases the cells are held 

 together in masses, called zeoglcece. An endospore is formed some- 



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