ABSTRACTS 101 



instead of water gave much more consistent counts, and in most cases 

 followed closely the sodium asparaginate agar, surpassing it in one or 

 two instances. Molds quite frequently affected the ease in counting 

 in the albumen agar, but less so in the ammonium nitrate-urea agar. 

 In the case of the asparaginate agar, however, there was no difficulty 

 experienced from this cause. 



It was also observed that inasmuch as all soils do not behave in the 

 same manner toward the different media it is essential to use several 

 soils in the comparisons; otherwise misleading results may be obtained. 



Differences between the counts on the various media were not as 

 large as might be expected and there seems to be no justification for the 

 belief that any particular one will be most satisfactory in all cases. 



Bacteria, Actinomyces, and Fungi in Soils. Selman A. Waksman. 



This investigation has been undertaken with a view to demonstrate 

 the relationship between these three groups of microorganisms in 

 different soils and at different depths. Soils of different texture and 

 structure were used, and samples taken at six different depths. A six- 

 day incubation period has been used for the counts of the bacteria 

 and fungi and a fourteen-day period for the actinomyces counts. The 

 results indicate that soils rich in bacteria are also rich in fungi and 

 actinomyces. The largest numbers of all the three groups occur within 

 the upper eight inches of the surface soil. The bacteria decrease regu- 

 larly with depth, in numbers and also in percentages relative to the 

 total numbers of microorganisms. The numbers of fungi decrease also 

 with depth and they almost disappear below eight to twelve inches. 

 The actinomyces numbers decrease with depth, but below eight to 

 twelve inches their numbers remain constant up to thirty inches, and 

 their percentage relative to the total numbers of microorganisms in- 

 creases regularly with depth, because the bacterial numbers decrease, 

 and fungi almost disappear. At a depth of 1 inch the bacteria form 

 81 to 86.5 per cent, fungi 6.2 to 7.1 per cent, and actinomyces 7.3 to 

 12.1 per cent; at 30 inches the bacteria form 16.4 to 42.1 per cent, fungi 

 to 5.6 per cent, and actinomyces 52.7 to 83.6 per cent of the total 

 microorganic flora of the soil developing on agar plates. The actino- 

 myces form a numerous group of soil microorganisms, especially in the 

 ower soil depths; over 30 species of them have been isolated. The 

 following groups of fungi occur in the soil in the largest numbers: 

 Penicillia, Mucors, Aspergilli, Cladosporia, Trichodermae, Fusaria, 

 and Alternaria. Many more fungus types have been isolated, but 

 their numbers are limited. 



FOOD 

 Under Supervision of Charles Thom 



Comparison of the Number of Water Bacteria Growing on agar at 37° C. 



and on Gelatin at 20°C. Fred W. Tanner. 



The recommendation of the Committee on Standard Methods for the 

 Examination of Water and Sewage of the American Public Health 



