INSTITUTE AND COLLEGE, PUSA, FOR 1910-11. 13 



soils will best serve as culture media for those bacteria, 

 naturally present in them, on which the processes of con- 

 version of the oro'anic nitrosren of humus into assimilable 

 nitrates depend. 



A special study has been made of the effect of hot 

 weather ploughing on the bacteriological content of the 

 soil, and the possibility of a bacteriological explanation of 

 the undoubted increase in fertility resulting therefrom. Tt 

 was found that the net result is an extremely rapid forma- 

 tion of ammonia, part o^f which becomes available to plants 

 and part of which is lost. Depletion of the soil nitrogen 

 is a necessary consequence and the maintenance of fertility 

 must depend on the restoration of this by green manuring 

 or otherwise. 



A bacterial disease of tobacco occurring in Rangpur 

 was investigated by Mr. Hutchinson. It was found to be 

 caused by a strain of Bacillus solanacearum, an organism 

 known to cause disease in several cultivated crops, such as 

 potato, brinjal and tomato. The Rangpur strain differs 

 from those described in America and Japan in some of its 

 pathogenic features. 



A disease of the Eri silk- worm, which causes havoc in 

 the broods at certain times of the year, was also studied. 

 It was found to be associated with the presence of bacteria 

 in the intestine. 



Certain preparations known as Ratin and Trope Ratin, 

 prepared in Copenhagen, have been widely recommended 

 as rat exterminators, and have been suggested for use in 

 India, both with a view to checking plague and to protect 

 crops against the ravages of field rats. Mr. Hutchinson 

 carried out tests of these preparations. Ratin was found 

 to have lost its virulence, but it is suggested that this might 

 be recovered by preparation in India. Trope Ratin was 

 found effective within a limited time after its preparation, 

 but its cost precludes any possibility of its use on a large 

 scale by cultivators. Neither can be recommended for 

 employment at present. 



