13 



soil exert a very distinct action on the bacterial flora. The usual 

 result is to produce at varying periods after treatment an enormous 

 rise in the number of certain special organisms. This is seen not 

 only in cases where the substance is known to be attackable by 

 certain bacteria, e.g., alcohol and phenol, but in others such as 

 quinone, where such action was not expected. The new flora is not 

 the normal soil flora, although with the very mildly acting antiseptics 

 the old flora may persist in approximately its original complexity 

 but certainly in no greater numbers. The predominant part of the new 

 flora is very much simpler than that remaining after treatment with 

 the easily volatile but potent antiseptics. The colonies are all very 

 slowly growing and consist of only two or three species of bacteria. 

 Determinations of the nitrogen present in the soil as ammonia and 

 nitrate show that the new flora does not produce ammonia. When 

 the abnormally high numbers fall off the condition finally attained 

 depends on the intensity of the initial action : phenol and cresol in 

 weak doses leave a flora which is similar in character to that arising 

 after normal partial sterilisation and produces more ammonia than 

 that of the untreated soil. None of these non-volatile antiseptics, 

 however, leads to such a marked increase in the amount of ammonia 

 and nitrate present after an incubation period as do the volatile 

 antiseptics. 



The curves obtained for the numbers of bacteria present after 

 the treatment of the soil with non- volatile antiseptics are remarkably 

 similar to those obtained by Hutchinson and MacLennan with 

 Woburn soil treated with various doses of quicklime. The increased 

 numbers are attributed to an increased supply of food : in these 

 experiments it is difficult to avoid the conclusion that the bacteria 

 are actually feeding on the antiseptics. 



The alcohols proved curiously ineffective : formaldehyde also 

 was less potent than was anticipated, behaving in weak doses very 

 much like the open chain hydrocarbons. 



IV. "The increased Nitrate Content of a Soil subjected to 



Temporary Drying in the Laboratory.'' Walter 

 Buddin. Journal of Agricultural Science, 1914. 6, 

 452—455. 



A remarkable effect of drying a soil was observed in the fore- 

 going experiments. Soils spread out to dry were found on moisten- 

 ing to have undergone practically no change in bacterial numbers 

 or in nitrate content and to resemble in every point tested similar 

 soils that had remained moist. But at the end of a month it was 

 found that the nitrates had increased to a considerably greater extent 

 in the soil that had been dried although there was no difference in 

 bacterial numbers. The effect closely resembles that of treatment 

 with volatile mild antiseptics. 



V. "Methods of Estimating Carboliydrates." II. "The 



Estimation of Starch in Plant Material." W. A. 

 DAVIS and A. J. Daish. Journal of Agricultural Science, 

 1914. 6, 152—168. 



A careful study of the existing methods of estimating starch in 

 plant material has shown that they are unreliable and a new process 

 has been worked out which gives more accurate results. 



