CHAPTER II. 



GENERAL PHYSIOLOGY OF BACTERIA THE EFFECT 

 OF ENVIRONMENT ON BACTERIA. 



A. RATE OF REPRODUCTION. 



B. MOTILITY: RATE OF MOTION. 



C. SPORULATION: GERMINATION OF 



SPORES. 



D. LONGEVITY. 



E. MOISTURE: DESICCATION. 



F. OXYGEN. AEROBIOSIS AND ANAERO- 



BIOSIS. 



G. TEMPERATURE. 



1. General. 



2. Cold. 



3. Heat. 



H. HEAT PRODUCTION. 



I. LIGHT AND ELECTRICITY. 



J. GRAVITY, OSMOTIC PRESSURE, AGI- 

 TATION AND CHEMOTAXIS. 

 K. ENZYMES, TOXINS. PTOMAINS. 

 L. PIGMENTS. 



1. Photodynamic. 



2. Phosphorescent. 



3. Fluorescent. 



4. Chromogenic. 



M. SYMBIOSIS, ANTIBIOSIS, COMMENSAL- 

 ISM. 



N. MEDIA COMPOSITION AND REAC- 

 TION. 



O. GROWTH IN ANIMAL BODY. 



A. RATE OF REPRODUCTION. 



ONE of the striking characteristics of the Bacteriacese is their rapidity 

 of reproduction. Among the most actively growing types of bacteria, 

 as, for example, the cholera vibrio, successive generations may appear 

 at intervals as frequent as every fifteen minutes when the environ- 

 mental conditions are most favorable: that is to say, ninety-six genera- 

 tions are theoretically possible in twenty-four hours. If this rate of 

 reproduction could be maintained for three days, the progeny of a 

 single organism would occupy a space not less than that of the com- 

 bined waters of the earth. Fortunately, nature imposes many restraints 

 which limit the numbers of bacteria. The rapid accumulation of waste 

 products, the exhaustion of nutrient material, and the enormous 

 death rate in culture media even after a comparatively few hours' 

 growth, together with other factors restrict development to such a 

 degree that the actual number of living descendants of bacteria in 

 cultures or in nature falls far short of the theoretical number. Many 

 bacteria develop more slowy than this, however. They may require 

 hours or even days to arrive at maturity. The tubercle bacillus, for 

 example, grows comparatively slowy in artificial media (where such 

 observations are of necessity made), and the frequency of septation, 

 even in the most rapidly growing bacteria, is greatly affected by 

 environmental factors. 



