4 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



large scale and sold in the form of tablets. The tablets, consisting 

 of slowly dried cultures mixed with milk sugar, are taken as such or 

 after having been added to sterile milk, thus effecting the souring of 

 the same. In addition to tablets of Bacillus lactis acidi and Bacillus 

 bulgaricus, a mixture of bacteria and yeast capable of producing 

 lactic acid fermentation of milk is sold under the name of " Kefir 

 fungi." Carter has made an examination of commercial cultures 

 of Bulgarian Bacillus. (Jour. A. Ph. A., 1919, 8 p. 179.) 



Very great interest has been aroused in the manufacture of 

 nitrogen-fixing bacteria in cultures for the use of farmers. Prob- 

 ably no question is of greater fundamental importance to the agri- 

 culturist than the supply of nitrogen to the soil. It has been known 

 for very many years that nearly all other plants except the Legu- 

 minosase (clover, alfalfa, soy beans, etc.) rob the soil of its nitrogen 

 while plants of this family serve to enrich it in nitrogen, hence they 

 have been called " collectors or accumulators of nitrogen." For 

 more than a century it was known that the Leguminosse produced 

 nodules or tubercles on their roots which were supposed to be evidences 

 of disease in the plants. In 1836 Treviranus found that these nodules 

 were normal growths, and in 1865 Woronin discovered in them cells 

 that were filled with bacteria. Hellriegel in conjunction with Wil- 

 farth carried on a number of investigations and arrived at the incon- 

 trovertible conclusion that the production of nitrogen by leguminous 

 crops was through the absorption of atmospheric nitrogen and con- 

 nected with the development of the nodules on the roots of these 

 plants. Beyerinck in 1888 isolated the bacteria and studied them 

 and their products in artificial media. The organism found in the 

 nodules on the roots of the Leguminosa3 is a single species of bacillus 

 known as Pseudomonas radicola. Prazinowski in 1889 inoculated 

 pure cultures into leguminous roots with successful results, and since 

 that time very much work has been done by manufacturers to 

 supply farmers growing leguminous crops with cultures of nitrogen- 

 fixing bacteria which would give them the maximum yield of crops. 

 This is particularly important where the leguminous crops are used 

 in rotation in a soil where the nitrogen-fixing bacteria are desirable. 



In the brief space allotted in a few pages it is impossible to 

 adequately cover even the more important phases of applied bac- 

 teriology. Mention cannot be made of many products which are 

 based upon the presence of bacteria or which are due to bacterial 

 action, neither can a detailed discussion be given relative to many 

 industrial operations which depend upon bacterial activity, such as 

 the curing of vanilla, the fermentation of tobacco, the manufacture 



