112 PHYSIOLOGY OF THE BACTERIA. 



The bacteria present in this respect numerous va- 

 riations according to the species and the period of 

 development which they have attained. In the 

 state of permanent spores, they are extremely ten- 

 acious of vitality. They resist for a long time 

 not only dessication, but a considerable elevation 

 of temperature. 



Among the bacteria, some are developed in liq- 

 uids, — the greater number, — others upon damp 

 surfaces. The former can live in fresh water, sea- 

 water, thermal waters, and the liquids of animal 

 or vegetable organisms, etc. A surprising fact 

 is, that the composition, so different, of fresh and 

 sea water appears to have no influence upon the 

 bacteria. We find in both all the species, from 

 Bacterium termo to Spirillum volutans. 



Nitrogen. — Pasteur has demonstrated that it is 

 not necessary that the nitrogen which is to serve as 

 nutriment to the bacteria should be in the form of 

 albumen, but that these organisms can take posses- 

 sion of it in the form of ammonia. 



In fact, in Pasteur's solution, composed as fol- 

 lows : — 



Distilled water 100. 



Sugar candy 10. 



Tartrate of ammonia .... 1. 



Ashes of one gramme of yeast . 0.075. 



the bacteria increase sometimes with such rapidity 

 that they interfere with the development of the 

 alcoholic ferment. 



