416 



SCIENCE 



[N. S. Vol. XXXVIII. No. 977 



to most soil organisms nor to many other bacteria. 

 A possible standard method is here suggested for 

 revivifying the bacteria that do not grow under 

 such conditions. The bacteria are to be divided 

 into five groups: 



1. Growing well in plain broth at 37° C. 



2. Excluded from group 1, but growing well in 



plain broth at 20° C. 



3. Excluded from groups 1 and 2, but growing 



well in dextrose broth at 37° C. 



4. Excluded from groups 1 2 and 3, but growing 



well in dextrose broth at 20° G. 



5. Excluded from all four groups, but growing 



well on surface of agar. 



Each of these groups is to have its own method 

 of revivification, as follows: 1, in plain broth at 

 37° (as at present) ; 2, in plain broth at 20° ; 

 3, in dextrose broth at 37°; 4, in dextrose broth 

 at 20° ; 5, on agar slants. This classification in- 

 cludes most soil bacteria and many others; but 

 further groups may be added as they prove neces- 

 sary. These groups are somewhat similar to the 

 groups of the bases recognized by chemists in 

 qualitative analysis. Like the chemical groups, 

 they are to be disregarded after the unknown has 

 been determined. 



The Ammonifying Efficiency and Algal Content 

 of Certain Colorado Soils: Walter G. Sackett. 

 The power to transform organic nitrogen into 

 ammonia is a property common to many cultivated 

 Colorado soils. Soils in the incipient stage of 

 the niter trouble appear to surpass our normal 

 soils in ammonifying eifieiency. Compared with 

 soils from other localities, our niter soils excel 

 in ammonifying efiiciency to a very marked de- 

 gree. Nineteen of the thirty-one soils examined 

 have ammonified cottonseed meal more readily 

 than the other nitrogenous materials employed ; the 

 remaining twelve have broken down in the dried 

 blood most easily; twenty -six have formed am- 

 monia from alfalfa meal more readily than from 

 flaxseed meal, and with five the reverse has been 

 true. The maximum per cent, of ammonia pro- 

 duced in seven days by any soil from 100 mg. of 

 nitrogen- as cottonseed meal was 51.98 per cent.; 

 as dried blood 52.64 per cent.; as alfalfa meal 

 34.85 per cent.; as flaxseed meal 12.15 per cent. 

 Algae occur abundantly in many cultivated soils 

 of Colorado. Twenty-one different species of algae 

 were found in the soils examined. With but two 

 exceptions, all the species found belong to the 

 blue-green algffi (Cyanophyce».) The family Nos- 

 tooacesB is best represented. There is a predom- 

 inance of forms possessing thick, gelatinous 



sheaths. This paper is published in full as Bulle- 

 tin 184 of the Colorado Experiment Station, Fort 

 Collins, Colorado. 

 Nitrogen Fixation hy Organisms from Utah Soils: 



E. G. Peterson and E. Mohr. 



This paper is a preliminary note in a proposed 

 extensive investigation regarding the fixation of 

 nitrogen in Utah soils and the r6le played by 

 microorganisms in this action, together with the 

 various agencies influencing bacterial action. 

 Samples of soil from which the organisms de- 

 scribed were isolated were taken weekly from 

 January 9 to November 4, 1912, from Greenville 

 Experiment Farm, Utah Experiment Station. 

 100 c.c. portions of mannite solution were inocu- 

 lated with 10 grams of soil and incubated at 20° C. 

 After ten days' incubation subcultures were made 

 in mannite solution and incubated for ten days at 

 20° C. Isolations were made from plates which 

 were made from these subcultures. Several types 

 of colonies were formed, but only three appeared 

 that grew readily and for a long period on man- 

 nite agar. The paper describes these three forms. 

 One of the three forms was undoubtedly Azoto- 

 iacter cliroococcum, the other two heretofore un- 

 described in western soils. Type No. 1 fixed 5.335 

 mg. of nitrogen in twenty days in mannite solu- 

 tion, average of 15 tests; type 2 (Asotoiacter 

 cliroococcum) fixed 5.616 mg. of nitrogen in 

 twenty days, average of 10 tests; type No. 3 fixed 

 5.588 mg. of nitrogen in twenty days, average of 

 12 tests. Analyses were made from January 9 to 

 October 28 to determine if possible any marked 

 seasonal variations in nitrogen fixation. The tech- 

 nique involved the addition of definite quantities 

 of soil, taken under standard conditions, to man- 

 nite solution, the amount of nitrogen in the soil 

 being subtracted from the amount of nitrogen 

 present at the end of twenty days in order to 

 determine the amount fixed. The variation was 

 found to be very marked from week to week with- 

 out apparent regularity, a marked increase in fixa- 

 tion power being noted from the middle of May 

 to the end of June. Isolations were made from 

 these impure cultures to determine the presence of 

 the three colony types described in the paper. 

 Types No. 1 and 3 were present in the majority 

 of samples, type No. 1 predominating in all cases. 

 Type No. 2 was present once in April, twice in 

 June and once in September. Further work is 

 being done on the three forms isolated. 



A. Parker Hitchens, 



Secretary 

 {To he concluded) 



