558 ABSTRACTS 



The cellulose-dissolving bacteria isolated from soils by means of the 

 cellulose agar plate method, have the power of dissolving the cellulose 

 of alfalfa. Twenty-five species of cellulose-dissolving bacteria dis- 

 solved alfalfa cellulose as readily as that prepared from filter paper. 



Thirty-six species of this type of bacteria have been isolated and 

 their cultural and morphological characteristics are given in detail. 

 Fifteen new species are included. 



A provisional key for identifying and comparing species of bacteria 

 which dissolve cellulose is appended. 



Many of the data called for by the card of the Society of American 

 Bacteriologists seem to have little significance in the separation of mem- 

 bers of this group. 



Filamentous fungi and actinomyces also unquestionably play an im- 

 portant role in the destruction of cellulose in nature. — Z. N. 



Actinomyces of the Soil. Selman A. Waksman and Roland E. Curtis. 



(Soil Science, 1916, 1, 99-135, 3 plates.) 



Seven different types of soils from different localities and under dif- 

 fering chmatic and cultural conditions were used. Brown's albumen 

 agar, slightly modified, was used for isolation of the actinomyces from 

 the soil and for counts. Each organism isolated was studied on Cza- 

 peck's solution, agar, potato, and on 15 per cent gelatin in distilled water. 



All the actinomyces studied liquefy gelatin and they may be divided 

 into two groups depending on their differences in color production, one 

 browning the liquefied portion, the other remaining colorless. A char- 

 acteristic of some species is the production of an aerial mycelium on 

 gelatin. 



The numbers of actinomyces decrease with soil depth, but their num- 

 bers, relative to those of bacteria and fungi, increase. 



Thirty species of actinomyces are classified, and their morphology 

 and cultural characteristics on the above media are considered in detail. 

 A key is included facilitating their identification. 



The average optimum, maximum and minimum temperatures are 

 30°C., 50°C. and 15°C. respectively. The actinomyces do not play any 

 appreciable role in the soil as ammonifiers; they readily assimilate NO2, 

 NO3, NH3 and organic compounds of nitrogen and characteristically 

 reduce nitrate to nitrite, but not to free nitrogen or NH3. 



Actinomyces are strong cellulose decomposers and this fact in com- 

 bination with their weak ammonia production leads the author to think 

 that the probable role of the organism in the fertility of the soil lies in 

 the formation of humus. Therefore, in arid soils where cellulose destruc- 

 tion has been found to be extremely rapid, actinomyces should be ex- 

 pected in abundance. — Z. N. 



Some Factors that Influence Nitrate Formation in Acid Soils. E. B. 

 Fred and E. J. Graul. (Soil Science, 1916, 1, 317-338, 1 ph) 

 Acid soils do not possess a strain of nitrifying bacteria especially re- 

 sistant to soil acidity. The nature of the compound to be nitrified 



