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INS'I.'l'l'U'I'E AND co r,rJEGE, PUSA, FOR 1910-11. 13soils will best serve as culture media for those bacteria,naturally present in them, on which the processes O'f conversionof the organic nitrogen of humus into assimilablenitrates depend.A specia] study has been made of the effect of hot'weather ploughing on the bacteriological content of thesoil, and the possibility of a hacteriological explanation oftho undoubted increase in fertility resulting therefrom. Itwas fOllnd that the net result is an extremely rapid formationnf ammonia, part nf which becomes available to plantsa,nd part of which is lost. Depletion of the soil nitrogenis a ncce::;sary consequence and the maintenance of fertilitymust depend on 111e reRtoration of this by green manuringor otherwise.A bacterial disease of tobacco occurring in Rangpurwas investigated by Mr. Hutchinson. It wa::; found to bet:auscd by a strnin of Badllus solanacearum, an organismknown to cause disease in several cultivated crops, such aspotato, brinjal and tOll1nto. The Rangpur strain differsfrolll. ·those described in Amrrion. and Japan in some of itspatbogenie features.A diseas(~ of tlw Ed silk-worm, whicll canses havoc inth(' hroods at l:t~I·tain ti rnes of' t.he year, waH also studied.It W[l.H found to l)(~ associat(1(l with Ow presence of hact.fria,in tlw intestine.Certain preparations known as Rat.in a,nd Trope Ratin,prc'pare'a in Copenhngcn, have been widely recommendedns rat exterminators, and Iuwe heen suggested for use inIndia" hoth wit.h a view to ohecking plague and to protectcrl)ps against the ravages of field rats. Mr. Hutchinsoncarried out tests of these prepa,rations. Ratin WfiS ·foundto have lost its virulence, but it is suggested tha,t this mightbe reoovered by preparation in India. Trope Ratin wasfound effective within a limited time after its preparation,but its cost precludes any possibility of its use on a largesca,le by cultivators. Neither can be recomm~nded foremployment at presont,