DEVELOPMENT OF THE BACTERIA. Ill 



closed abcesses, in cysts, in urine drawn from the 

 bladder, etc. 



2. NUTRITION AND RESPIRATION OF THE 

 BACTERIA. 



The bacteria, being organisms composed of a 

 cell membrane of cellulose, and of protoplasmic 

 contents, deprived of chlorophyll, must receive 

 nutriment and respire in the same manner as all 

 the colorless vegetables and all the inferior animals 

 deprived of special apparatus, that is to say, by 

 end osmotic absorption. 



Although the media in which the bacteria de- 

 velop are various, yet, from the point of view of 

 the nutritive function, they act everywhere^ ac- 

 cording to the same laws. No matter in what 

 medium they live, they must have water, nitro- 

 gen, carbon, and oxygen, as well as certain min- 

 eral salts which enter, but in quantities exceedingly 

 minute, into the chemical constitution of all organ- 

 ized bodies. 



Water. This element is indispensable to the 

 active life and development of the bacteria. Dessi- 

 cation arrests completely the movements of those 

 which are mobile, and the functions of all the 

 bacteria in general ; but it does not kill them, 

 at least if it be not prolonged beyond a certain 

 time. The micrococci of different kinds of virus 

 are examples of the continued vitality of these 

 organisms after dessication for a considerable time. 



