120 EXPERIMENT STATION EECORD. 



Methods of soil toxicology, O. Sciikeinek and E. C. Shorey {Abs. in Sci- 

 ence, n. ser., 27 (WOS). Xo. mo, pp. 295, 296). — This is r.n abstract of a papei' 

 presented at the Cbica.^o meeting of the American Chemical Society. The impor- 

 tance of working ont refined methods for the detection, isolation, and study of 

 the small amounts of toxic organic bodies which are believed to exist in soils 

 is pointed out, and the authors outline " methods of separating the organic mat- 

 ter from the large mass of Inorganic material, and further seiiaration of the pure 

 organic body from the extraneous organic matter by methods of extraction, solu- 

 tion, precipitation, distillation, etc. The specific methods by which several harm- 

 ful organic compounds have already been isolated from unproductive soils are 

 given to illustrate the general principles involved." 



The cause of soil sickness (Mark Lane Express, 98 (1908), No. 3985, p. 

 ]'i5). — This article reviews briefly the evidence supporting the view that soil 

 sickness is due to poisonous excretions of the roots of plants. 



Bacteriological investigations -with reference to the drying of soils, O. 

 Rahn {Cenihl. Bald, [etc.'l, 2. AM., 20 (1901), \o. 1-3, pp. 38-61, pi. 1, fig. 1 ; 

 ahs. in Chem. Ztg., 32 (1908), No. 9, Rcpert., p. Jf7). — From a large number 

 of studies on the formation of acid in sugar solutions, carbon dioxid in sugar 

 solutions containing calcium carbonate, and ammonia in urea and i)eptone solu- 

 tion, the conclusion is reached that bacterial changes go on much more rapidly 

 in soils dried at room temperature than in similar samples kept moist or in 

 the original moist soils. The difference in this respect between the dry and 

 moist samples was in the case of garden soil about 60 per cent and in ordinary 

 farm soil 10 to 30 per cent, but in case of a light sandy soil inappreciable. The 

 rapidity with which the drying took place had very little Influence on the differ- 

 ence in bacterial change. Since the number of organisms in soil samples was 

 invariably decreased by drying it is difficult to explain the difference In bac- 

 terial activity. It can not be explained on the basis of physical properties, since 

 such differences were observed in case of soil samples suspended In water and 

 in extracts of the soils. Neither can decomposition of the soil constituents fur- 

 nish an explanation, because with the liberal addition of potassium phosphate 

 and asparagin similar differences were observed. Variations in the amount of 

 nitrates in the soil were also without effect on the bacterial activity. Whatever 

 the substances producing the difference it must be undecomposable by boiling 

 and capable of passing through filter paper. It is not clear whether it acts 

 by reducing bacterial activity in the moist soil or accelerating It in the dry 

 soil. Dry soils lose the greater part of their Intensified putrefactive power and 

 do not differ materially from the original moist soils after they have been 

 moistened about 24 hours. Mustard plants grew better in soils which had 

 become dry than in those which had been kept moist continuously. 



Tests of Remy's method of judging soils indicate that this method may give 

 erroneous results if great care is not taken to prevent the loss of moisture from 

 the cultures. 



The influence of the composition of the medium upon the solvent action of 

 certain soil bacteria, C. W. Bkown (Rpt. Mich. Acad. Sci., 9 (1907), pp. 160-162, 

 figs. 3). — A study of the solvent action of a large number of soil bacteria on 

 rock phosphate, bone, pure trlcalcium phosphate, dicalcium phosphate, and cal- 

 cium carbonate is briefly reported. 



The results show that 12 out of 25 bacteria isolated from soil exerted a 

 definite visible solvent action on the substances named when supplied with some 

 form of sugar in the nutrient medium. " One which produces no gas but a 

 larger amount of acid from sugars than any of the others, shows the greatest ac- 

 tion upon the calcium carbonate, while other germs which produce gas — 

 largely carbon dloxld — but not as much acid as the former, give an action mor'e 



