INSTITUTE, PUSA, FOR 1919-20 ■ 41: 



From the above table it is evident that, in general, the 

 seedlings grown in "wheat," " gram," and " rahar" water 

 throve better than in the " blank test " solution, and that 

 seedlings grown in distilled water fared best. These ob- 

 servations led to the conclusion that the positive results 

 obtained in the experiments recorded in the memoir were 

 probably due to the concentration of the salts present in 

 the well water and not to toxic excretions. This is con- 

 firmed by an examination of the figures for the "total 

 solids' in the solutions. The concentration of "blank" 

 water in which the seedlings grew the worst was the 

 highest, whereas, the best results were obtained in the dis- 

 tilled water. The results obtained from the other 

 ;< waters ' were intermediate in character and approxi- 

 mately proportionate to the concentration. In short, the 

 present series of experiments point to the conclusion that 

 increased concentration of any solution beyond a certain 

 limit leads to a toxic effect by some or all of the component 

 salts present in the solution. The strength of the solution 

 in the original experiment recorded in the memoir works 

 out approximately to 112 per cent., a concentration which 

 no doubt will prove toxic to any plant. The presence of an 

 alkaloid which the author inferred was the character of 

 the excreted toxins could not be demonstrated in the pre- 

 sent experiments, and consequently it is only possible to 

 conclude that the effect which had been ascribed to toxic 

 excretions, is in reality due to the high concentration of 

 salts in the solution employed in the final stages of the ex- 

 periment. An account of the present experiments which 

 have been carried out by Mr. Mukerji has been submitted 

 for publication in the " Agricultural Journal of India." 



IX. Carbon dioxide in soil air. 



Periodical determinations of carbon dioxide were made 

 in the soil air of three plots in the Botanical Area. Of 

 these the first plot w r as grassed down, the second was 

 grassed down but was partially aerated by trenches, and 



