124 



KNOWLEDGE. 



Aprh-, 1911. 



The use of volatile antiseptics seems to have been 

 first introduced by Oberlin for the destruction of the 

 phylloxera disease of the \-ine. The fa\-ourable 

 results obtained bv the use of carbon disulphide led 

 to trials with other crops \\ itli equally good results. 

 ()b\ioush-. the benefit could not be due to any 

 diminution of plant diseases, Init to a stimulation of 

 processes concerned in the nutrition of the plant, or 

 of those occurring in the soil itself. Koch regarded 

 this increased fertility as being due to a stimulation 



\'arious crops were grown in these soils — buckwheat. 

 r\-e, mustard and wheat — and the results obtainetl 

 with r\e ma\- be taken as tx'iiical. Table .\ gives 

 various data as to the weights produced, while 

 Figure 1 is from a photograph of some young wheat 

 plants growing in the respective soils. 



The use of partially sterilised soils for plant 

 experiments has two distinct effects: there occurs a 

 striking increase in the weight of crop, varying from 

 twent\' to over two hundreil per cent. and. further, 



Table A. 



of the plant hv small (]uaiitities of the antiseptic 

 remaining behind in the soil after treatment, while 

 Hiltner and Stormer attributed it to the destruction 

 of nitrate-decomposing bacteria, and to a subsequent 

 growth of humus decomposers — the various species 

 of Stre[)tothrix. Further it was sujiposed to be due 

 in part to an increased growth of those bacteria 

 which produce nitrates or assimilate atmospheric 

 nitrogen. 



For some time this problem has been studied b}' 



there is almost invariabh' an increase in the nitrogen 

 content of such cro()s. Other experiments have shown 

 tliat the latter is due to an assimilation of nitrogen as 

 ammonia instead of as nitrates as is normally the case; 

 mild antiseptics and moderate heat are sufficient 

 to destroy the nitrifying organism. In order to 

 follow the various chemical and bacterial changes, 

 samples of the respective soils were stored in 

 sterilised bottles and analvsed at certain intervals. 

 Chemical analyses revealed the fact that a rapid 



TAIU.E B. 



Dr. E.J. Kussell and the Author, and the probahilit)- 

 of the existence of an altogether different factor has 

 been indicated. Our initial experiments were 

 designed to show the actual increase in fertility as 

 measured 1)\- plant growth. Samples of soil were 

 carefulK' sie\ed and filled into glazed pots, which 

 were then di\ided into three sets. One set remained 

 untreated, a second set was heated to 100" C. for 

 three hours, while a third was partially sterilised by 

 the addition of four per cent, toluene and afterwards 

 freed from this substance by exposure to the air. 



decomposition of the nitrogenous constituents of the 

 treated boils, witii amnicniia ]iroduction. was taking 

 place, while the untreated soil slowl_\- produced 

 nitrates. Bacteriological anah'ses demonstrated an 

 initial drop in the number of organisms present, with 

 a subsequent rapid increase, until at the end of a few 

 weeks the tolueiied soils contained ii\e to eight times 

 the number of bacteria as the untreated soils. Thi'se 

 changes are shown in Table I!. 



The connection between bacterial activity and the 

 production ot [ihiiit food is obvious from the above 



