H. 15. Hutchinson and J. Clayton 145 



moistened with a 0-05 per cent, .solution of di-potassium hydrogen 

 {phosphate. The paper was infected by means of a suspension of garden 

 soil, ditch mud. humus or dry leaves, and incubated at 24°-28°. After 

 four to five days yellowish brown spots were produced on the paper which, 

 at a later stage, became pulpy owing to the growth of the two organisms 

 referred to above, until finally the individual fibres of the paper were 

 enveloped in a "micrococcus mucilage." Van Iterson states, however, 

 that decomposition of the paper could never be obtained by the use of 

 such pure cultures as he was able to isolate from decomposing paper. 

 His reference to the "micrococcus mucilage" encountered in crude 

 cultures is interesting in its relation to our own results, which are given 

 below. Van Iterson was also able to demonstrate the occurrence of a 

 considerable number of filamentous fungi which are capable of utilising 

 filter paper as a source of carbon. 



At a later date Christensen^ suggested the use of the cellulose 

 decomposing power of a soil as an index of soil fertility. According to 

 the amount of change undergone by strips of filter paper when reposing 

 on the surface of different soils, the latter were placed in one of five 

 grades — from i to — of biological potency. 



The first systematic investigations on aerobic cellulose decomposition 

 were those initiated by Kellerman and McBeth^ and subsequently 

 continued by McBeth and Scales^. The former paid particular attention 

 to the technique of cultivation and in this connection suggested the use 

 of a number of special media such as cellulose agar, potato agar, starch 

 agar, and an agar containing dextrose, mineral salts and ammonium 

 sulphate. By the preliminary use of "elective" cultures, and plating 

 out on the above media, they succeeded in isolating a number of 

 organisms of which three. Bacillus rossica, Bacillus amylolyticus and 

 Bacterium flavigena, were derived from cultures of anaerobic cellulose 

 decomposing organisms obtained from Omelianski. McBeth and Scales 

 examined soils from widelv separated regions of the United States and 

 isolated therefrom eleven species of bacteria while an additional four 

 species were obtained from other sources. All these organisms are 

 morphologically and physiologically distinct from Omelianski's hydrogen 

 and methane organisms and grow well on ordinary gelatine media, 

 although continued cultivation on such media is rapidly followed by 

 loss of cellulose destroying power. None of these species produced gas 



' Christensen, H. R., Cent. Bukt. Par. ii. liJlO. 27, 449-451. 



- Kellerman, K. F. and McBeth, I. G., Ibid. 1912, 34, 485-494. 



=> McBeth, I. G. and Scales, F. M., U.S. Dep. Agr., Bureau Plant Ind.. Bull. 260, 1913. 



Journ. of Agric. Sci, ix 10 



