292 



STATE BOARD OI~ AGRICULTURE. 



XXI. ACTION OF NITROGEN UPON THE SPECIFIC MICRO-ORGANISMS STUDIED. 



Nitrogen in this case is considered, or the residual gas left after the absorption of 

 oxygen from the air by the use of alkaline pyrogallate. Of the plate cultures, one set 

 remained in the air as check and the other set was placed in a jar from which the 

 oxygen was absorbed. The plates were made by the same methods used heretofore. 

 The results are tabulated in Table XIX. 



TABLE XIX. 



Nitrogen or the residual gas resulting from the absorption of oxygen from the air does 

 not appear to have the same detrimental effect upon these micro-organisms as either 

 the carbon dioxide or hydrogen. We are led to believe, therefore, that the gases them- 

 selves play an important part in the restraining influences exercised when these gases 

 are employed and the injurious effects observed may be counted as reaching beyond that 

 which may be considered as purely anaerobic conditions. There is a retarding and 

 inhibiting influence caused by carbon dioxide and also by hydrogen. In the case of 

 milk, it must of course be due to carbon dioxide alone so far as the action of a gas is 

 concerned. It is generally considered that hydrogen is not an inert gas when employed 

 for the cultivation of anaerobic bacteria (Novy-Cent. f. Bakt. XIV 58G). Liborius 

 has shown that carbon dioxide likewise is not suitable as an atmosphere for anaerobiosis 

 (Cent. f. Bakt. III-768). Fraenkel in the case of symptomatic anthrax bacillus and 

 malignant edema bacillus found carbon dioxide completely checking the growth and 

 apparently killing the bacteria (Zeit. f. Hyg. V-323). 



The conclusion reached regarding nitrogen should be regarded as indicative of a 

 wide influence exerted by gases in the production of anaerobiosis. While the prime 

 essential to anaerobiosis is an absence of oxygen, yet there must usually be associated 

 with this absence a substitute gas which necessarily imparts to the germ environment 

 favorable or unfavorable factors in the determination of active cell metabolism and 

 cell growth. It becomes therefore exceedingly difficult to definitely state the actual 

 conditions of anaerobiosis. 



Before arriving at a definite and specific notion of what is involved in the process 

 or aeration, other factors, other than carbon dioxide have to be considered. One of 

 these is the relation of acidity to the growth and increase of micro-organisms. 



