764 



SCIENCE 



[N. S. Vol. XXXIX. No. 1012 



Water 



Soil-extract. . 



Agar 



Gelatin 



Peptone. . . . 

 Albumin .... 

 Na. Asparag. 

 Dextrose .... 



MgS04 



K2HPO 



NH4H2POi.. 



KCI 



CaCl2 



FeCls 



Fe2(S04)3 



1,000 

 12 



1,000 

 12 



1,000 

 20 

 .05 



10 



1,000 

 15 



Trace 



900 

 100 



In the asparaginate agar the reaction should be 

 carefully adjusted to 0.8 per cent, normal acid to 

 phenolphthalein. The dextrose and asparaginate 

 should be added just before tubing. 



Some thirty-five comparative tests of the gelatin 

 with one or more of the other media have been 

 made. Various soils have been used for inocu- 

 lating. Incubation has been at 180° C. for seven 

 days with gelatin and fourteen with agar, which 

 allows a very high count (5-50 million in normal 

 field soil). The following figures (referred to in 

 terms of colonies on asparaginate agar as 100) 

 represent instances that seem to be typical: 



Case 1 100 170 68 57 113 



Case 2 100 85 75 Irregular 93 



About forty other tests have been made to de- 

 termine the best proportions of the various con- 

 stituents in the asparaginate agar. None have 

 proved more satisfactory than the above formula. 



As a result of this work the asparaginate agar is 

 highly leeommended. The only medium which 

 seems better, either in respect to count or to the 

 colony differentiation, is soil-extract gelatin; and 

 because of the addition of soil extract this gelatin 

 is not one that can be readily duplicated. The 

 only one of the media investigated which gives 

 a higher count than either of these is Fischer's 

 soil-extract agar, which does not allow good col- 

 ony differentiation. The detailed results of this 

 work are to be published as a technical bulletin 

 of the New York Agricultural Experiment Sta- 

 tion. 



Antagonism Between Salts as Affecting Soil Bac- 

 teria: Chas. B. Lipman. 



With Loeb's conception of physiologically bal- 

 anced solutions as a basis, the author has carried 

 on experiments dealing with a phase of the subject 

 hitherto regarded as of little significance, namely, 

 the antagonism between anions. The most striking 

 results have been obtained with such antagonism 

 between anions through the use of the so-called 

 alkali salts which commonly include sodium chlor- 

 ide, sodium carbonate and sodium sulfate. 



Results of antagonism between the anions of 

 these salts show that both as regards ammonifica- 

 tion and nitrification, it was possible to improve 

 the soil as a medium after it had been made toxic 

 for the bacteria in question, by means of any one 

 of these salts, through the addition of any other 

 of the three salts mentioned. Thus briefly, it was 

 possible at times to triple and quadruple the total 

 salt content of the soil and still make it a better 

 medium for ammonification and nitrification than 

 it was with one third or one fourth of the totaJ 

 salt content consisting, however, of but one salt. 

 The author claims for this great significance in 

 the direction of the management and control of 

 alkali land. 



Sulfofication in Soils: P. E. Brown and E. H. 



Kellogg. 



Recent work has shown that considerably larger 

 amounts of the element sulfur are removed froiB 

 soils by the growth of crops than has been sup- 

 posed. The inaccuracy of the old method used in 

 the determination of the sulfur in crops explains 

 the discrepancy. Soils have been shown to con- 

 tain in most cases only a limited supply of sulfur, 

 usually a smaller amount than of phosphorus. 

 The problem of the sulfur feeding of plants is 

 therefore coming to be of considerably more im- 

 portance than it has been in the past. The natural 

 means of returning sulfur to the soil is by the 

 use of farmyard manure or green manure and in 

 these materials it is added in a complex organic 

 form in the proteins. The sulfur in these must be 

 transformed into sulfates to be of use to plants. 



Here is where the sulfofying bacteria appear. 

 They are the agents which bring about the change 

 of organic sulfur into sulfates. Many questions 

 immediately arise in a consideration of this point. 

 Do soils have a sulfofying power? Can this be 

 determined? How? What is the relation of the 

 sulfofying power of soils to the sulfur feeding of 

 plants? etc. This work deals with the first ques- 

 tion and shows that soils do have a definite sulfo- 



