720 EXPERIMENT STATION EECORD. 



cent nonspore-producing, nonliquefiers, short rods, immotile or with polar 

 flagella ; trace, Micrococci, like the last group physiologically ; 15 to 45 per ceut 

 Actinomycetes. 



" Of these 6 groups all are strict aerobes except a few iu group 1 ; almost 

 without exception none produce gas from sugars; while acid production, 

 although common, is always very weak. 



" Each group comprises about 7 or 8 types, except the last two, in which 

 there are l)ut 1 or 2 types." 



In later investigations 40 more cultures were isolated from 4 different kinds 

 of soil fi'om other places in New York. " With few exceptions these cultures 

 seem to be the same kinds as those previously studied, although the relative 

 frequency of the types is different." 



The need of the development of a technique to determine the relative abun- 

 dance of different kinds of soil organisms is pointed out. 



Regarding' humus acids, B. Tacke, H. Suchting, et al. (Landw. Jahrb., J/l 

 {1911), Xo. 5, pp. 717-75-'f). — The results of experiments to test the accuracy 

 of the conclusion reached by A. Baumann and E. Gully from their investiga- 

 tions (E. S. R., 23, p, 715), namely, that there are no free humus acids, are 

 reported in detail, and include studies on the amount of acids liberated by 

 peat moss as compared with that liberated by starch, cellulose, and stearic 

 acid from tricalcium phosphate (1.5 and. 10 per cent solutions), sodium ace- 

 tate, barium acetate, and calcium oxalate under varying temperatures; the 

 absorption by peat moss, as compared with starch and gelatin, of alumina and 

 iron from their respective chlorids, and of iron from ferric hydroxid ; the 

 electric conductivity of peat moss extracts as compared with that of different 

 organic acids and of solutions of potassium chlorid; the acidity of leached 

 and unleached plant substances; the blue coloration of a mixture of potassium 

 iodid and iodate, and starch paste by different acids and acid-containing sub- 

 stances ; the inversion of saccharose by humus extract ; and the liberation of 

 hydrogen from a mixture of iron and. humus extract. 



It was found that the amount of phosphoric acid liberated from the tri- 

 calcium phosphate by peat moss increased with the proportion of peat moss 

 used, the amount of water remaining constant. With given amounts of peat 

 moss more phosphoric acid was rendered soluble when larger amounts of 

 tricalcium phosphate were used. Changes in the surface area of the soil 

 colloids by drying produced no change in the solubility of the phosphoric acid. 

 The colloidal character of the peat moss had no noticeable effect on the reac- 

 tion with tricalcium phosphate. Starch as a neutral colloid, did not render 

 soluble any phosphoric acid from tricalcium phosphate. 



Starch and cellulose, as neutral colloids, liberated no noteworthy amounts 

 of acetic acid or mineral acid from the salts of the alkalis or alkaline earths. 

 Peat moss, on the other hand, liberated considerable amounts of acetic acid 

 from the acetates and small amounts of oxalic acid from calcium oxalate. 

 No effect of the colloidal character of the peat moss was noticeable in the 

 reactions of these salts. 



Peat moss decomposed solutions of iron chlorid, decreasing the concentra- 

 tion to such an extent that nearly all the iron was precipitated from a 0.001- 

 normal solution. Peat moss adsorbed the iron from a solution of colloidal 

 ferric hydroxid, decreasing the concentration so that all the iron was adsorbed 

 from a 0.01-normal solution. Heating greatly decreased the adsorption of 

 iron from ferric hydroxid. Gelatin and starch adsorbed very small and, as 

 compared with peat moss, substantially smaller amounts of iron from dilute 

 solutions of ferric chlorid. Gelatin adsoi-bed very much smaller amounts of 

 iron from ferric hydroxid solutions than peat moss and adsorbed no iron from a 



