420 EXPERIMENT STATION RECORD. 



ever, thej- do not coutaiu euougli nitrate to supply tlie wants of the strongly 

 growing young plants and a niti-ate fertilizer is badly needed. Later the nitri- 

 fication in the soil is enough. 



The author studied the variation of the nitrogen content of the soil during the 

 period of vegetation with a good clayey chernozem soil taken from a sugar 

 beet field on which during the experiments no jilants were raised but which was 

 cultivated like the adjoining area under beets. The results show that the nitrate 

 nitrogen content of the surface soil in the spring was actually very small (as low 

 as 1.9 mg. per kilogram of dry soil). In the course of the summer it increased, 

 reaching in July and August a maximum of 41 mg. 



From the results of this and similar experiments the author draws the follow- 

 ing general conclusions : (1^ Timely, rational cultivation of the soil so as best to 

 preserve the humidity greatly furthers the accumulation of nitrates, (2) the 

 nitrification process in the chernozem soils is not at all or very slightly influenced 

 by manuring, (3) the plowing under of straw holds back the nitrification process 

 only during the earlier period, (4) plants sowed and then iilowed under for green 

 manuring, including leguminous crops, besides making the soil too dry during 

 harvest time, strongly impoverish it in assimilable nitrate nitrogen. Also, 

 later no beneficial influence of green manuring on the nitrification process has 

 been observed. — p. fireman. 



Soil bacteriological investigations, Maassen and Behn {Mitt. K. Biol. 

 Anst. Land u. Forstic, 1001. No. .'/, pp. ^3-3S). — This is a general statement 

 regarding the character of the work done along this line at the Biological Insti- 

 tute of Berlin. 



On the bacteria of the tubercles of various leguminous plants, Maassen 

 and MtJLLER {Mitt. K. Biol. An.sf. Land u. Forstic, 1907, No. J,, pp. Ji2-Ji-'i) .— 

 Observations are recorded which show an increase of from 1,248,0CK) to S,960,00<) 

 root tubercle bacteria of Trifoliiun pratensc in f^ gm. of soil in 4 days. 



Studies of the character of the tubercles produced on roots of leguminous 

 plants are referred to as leading to the conclusion that these tubercles are 

 abnormal growths of purely pathological nature. Contrary to previous ct)n- 

 clusions, the authors are of the opinion, in the light of their recent investiga- 

 tions, that the root tubercle bacterium is botanically identical in all cases 

 although modified somewhat in roots of different plants. 



As a result of a large number of experiments with different kinds of legumi- 

 nous plants the authors reach the conclusion that: (I) The oi-ganism of I'isuni 

 sativum will inoculate Vicia faba, V. sativa, V. villosa. Lens csculcnta, Lalhynts 

 sativus, L. odaratus, and L. silvcstris; (2) that of TrifoUum incarnatum will 

 inoculate T. pratensc; (3) that of Medicago sativa will inoculate M. lupulina 

 and Melilot us officinalis; and (4) that of Liipinitsliitciis will inoculate L.angus- 

 tifoUus and Ornithopns sativus. 'Vhe organisms of Ptiaseolus vulgaris, Soja 

 Idspida, and Rohinia pseudacacia will apparently not inoculate any other 

 plants. The same is probably true of the organisms of Coronilla varia, Ono- 

 hrychis satnva, Antliifllis viilncruria, Sarofhaninus scopariiis, Aniorpha fniti- 

 cosa, Caragana fruicscens, and Acacia lophanta, although these have not been 

 so fully studied as the others. 



The bacteria of leguminous plants, L. Lauvray {Jour. Agr. Prat., n. svr., 

 12 {1906), No. JfJf, pp. 549, 550). — A brief note is given reviewing practical tests 

 of pure cultures of these organisms. 



The action of carbon bisulphid on the bacteria of soils, Maassen and Behn 

 {Mitt. K. Biol. Anst. Land u. Forstw., 1901, No. Jf, pp. 3 8-Jf 2) .—The results of 

 plat and pot experiments are briefly sunnnarized, showing a great reduction 

 in the total count of bacteria immediately following treatment with cai'bon 

 bisulphid but later an unusual increase. Streptothrix organisms were decidedly 



