234 Bacteria in Relation to Country Life 



proper growth of the nodule-bacteria supplied on the 

 cotton. It was subsequently found, moreover, that the 

 method of preserving the tubercle-bacteria in a dried 

 condition on cotton was not so satisfactory as had been 

 supposed. Most of the organisms perish in the drying. 

 When the temperature and moisture changes of the 

 atmosphere are of considerable range, it is difficult to 

 preserve any of them in a dried state. 



The commercial preparation of the cotton cultures 

 received a serious check when it was discovered in the 

 experiments of several of our experiment stations that 

 such cultures failed almost uniformly to produce the 

 desired results. European tests of cotton cultures also 

 gave negative results, thus substantiating the conclu- 

 sions of the American experiment stations that no 

 reliance can be placed on the cotton method for the 

 distribution of efficient cultures of nodule-bacteria. 



The use of pure cultures in the United States is at 

 present subject to more or less uncertainty. The unsatis- 

 factory nature of the cotton cultures having been demon- 

 strated, pure culture material is sent out now in liquid 

 form, or as a growth on agar. The farmers are warned, 

 however, to utilize such cultures within the space of 

 ten days or two weeks, for the rapid deterioration of 

 the cultures after that period renders their value doubt- 

 ful. It is evident, at any rate, that further investigations 

 of cultures and culture methods are quite necessary. 



While there is reason to think that, in this country, 

 the employment of pure cultures is destined to occupy 

 a larger place in agricultural practice, the present un- 

 certainty makes it advisable to place more reliance in 



