Mar. 24, 1919 



Ammonification of Manure in Soil 



321 



A survey of the results in Tables I, II, and III shows that the number 

 of non-spore formers in the open pots of manured soil increased rapidly 

 for the first few days (see Table I, column 5). In every instance the 

 highest percentage of this group of organisms was reached within the 

 first week after the addition of the manure and this maximum point was 

 never less than 92.5 per cent, while in some cases it reached 97 per cent. 

 The results in the flasks were much more erratic and, while the per- 

 centage of non-spore formers often ran above 90 per cent of the flora, the 

 lines of increase and decrease were not so well marked as they were in 

 the pot experiments. This was undoubtedly due to the fact that con- 

 ditions of aeration and moisture content were decidedly abnormal. By 

 summarizing the three tables it was found that the non-spore-forming 

 organisms averaged 74. i per cent of the entire flora in both the pots and 

 flasks; the Actinomycetes 25.1 per cent, and the spore formers only 0.8 

 per cent. 



Table IV. — Results of the isolation of organisms from manured soil 



o Plain nutrient agar was used as medium for isolated colonies. 



While the data accumulated in the preceding experiments indicated 

 very strongly that the non-spore formers were the predominating organ- 

 isms in the manured soil, yet the proof was not absolute, because it was 

 based entirely upon the appearance of the colonies upon the plates. 

 Those colonies which possessed the characteristic spreading or filamentous 

 appearance of the typical spore formers were classified accordingly; 

 but some non-spore formers may thus have been inadvertently recorded 

 as spore formers, or some spore formers as non-spore formers. A number 

 of isolations were made, therefore, from the plates poured during the 

 series of experiments described above. All colonies which looked like 

 106546°--19 2 



