52 



OSWALD SCHREINER AND J. J. SKINNER 



on the plants noted were produced by the absorption of the 

 compound as such. Nitrite, nitrate, or ammonia were tested for 

 and found to be absent, or, in the case of ammonia, in traces 

 only. Although neither nitrate, nitrite, nor ammonia was found, 

 the plants nevertheless grew remarkably well and the only 

 conclusion justified by this experimental evidence is that this 



Whciit plants growing in culture solutions containing various porportions of 

 potash and phosphate, without and with nucleic acid. (Cultures marked N con- 

 tain nucleic acid.) 



compound is directly absorbed and assimilated. With the strict 

 chemical control exercised all possibility of any extended action 

 by bacterial or other external biological agencies seems excluded. 

 If such effects were produced in these experiments, they were 

 of only minor significance in the results obtained. Bacterial and 

 other microorganisms were excluded as far as possible, but no 



