. Annals of applied biology. Biology, Economic; Biochemistry. H. Gr. Thornton 265 which developed from a single diluted suspension of Rothamsted soil on media containing 0-05 per cent., 0-1 per cent, and 0-2 per cent, mannitol. Eight parallel platings of each medium were poured and incubated for seven days at 20° C, No significant differences in the number of colonies, on the different media, were found. It was decided to include 0-1 per cent, mannitol in the medium as this gives the maximum energy supply without increasing "; Attention was also turned to the effect of phos
. Annals of applied biology. Biology, Economic; Biochemistry. H. Gr. Thornton 265 which developed from a single diluted suspension of Rothamsted soil on media containing 0-05 per cent., 0-1 per cent, and 0-2 per cent, mannitol. Eight parallel platings of each medium were poured and incubated for seven days at 20° C, No significant differences in the number of colonies, on the different media, were found. It was decided to include 0-1 per cent, mannitol in the medium as this gives the maximum energy supply without increasing "; Attention was also turned to the effect of phosphate supply on the spreading of B. dendroides. The increase in area of surface growth of this organism was measured on media containing 0-2 per cent., 0-1 per cent., 0-05 per cent, and 0-025 per cent. K2HPO4 respectively. Variation of the concentration of K2HPO4 between these limits was found to be without significant influence on the "; 601- 0«2%KNO3_. Days gi'owth. Fig. 11. B. dendroides. Effect of nitrate content of medium on spreading. 3. Maintenance of Standard Eeaction. One of the features necessary in a medium to be used in quantitative work is that its reaction should not vary sufficiently to afiect the colony development. The reaction is commonly standardised just before sterilisation. It is during sterilisation that changes occur which are not always constant, so that uniformity in the sterile medium may be lost. In developing a medium, it is therefore important to consider the change in hydrogen ion concentration which will occur during sterihsation. If possible, the medium should be so constituted that this change shall not be sufficient to affect colony development. In this portion of the work, therefore, it was necessary, firstly, to ascertain the limits of change in reaction which might occur in the medium without affecting the number of colonies that. Please note that these images are extracted from scanned page images that may have been d
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