1048 EXPEEIMENT STATION RECORD. 



Reports of investigations conducted at the State experiment stations at Vester Hass- 

 ing, Askov, Tystofte, and Lyngby. 



FERMENTATION BACTERIOLOGY. 



Further studies on nitrogen-assimilating bacteria, Gerlach and Vogel 

 {Centhl. Bali. u. Par., 2. Aht., 9 {1902), Nos. 22-23, pp. 817-821; 24, x>p. 881-892).— 

 Experiments are described with Azotohacter chroococcum in cultures containing vary- 

 ing amounts of grape sugar. The authf)rs and others had previously shown the pos- 

 sibility of nitrogen assimilation by this and other organisms when grown in nutrient 

 media containing the proper carbohydrates. In the experiments here reported 

 from 1 to 15 gm. of grape sugar were added to each liter of culture medium and after 

 5 weeks' growth of the organism the nitrogen content was determined by the Kjel- 

 dahl method. Uniformly increasing gains are reported for each culture up to the 

 one receiving 12 gm. of grape sugar. Beyond this amount there was a decided fall- 

 ing off in the nitrogen increase. The amount of nitrogen taken from the air by these 

 cultures varied from 7.4 mg. to 127.9 mg. per liter of media. When cultures were 

 used to inoculate soils in which oats, mustard, and carrots were grown there was no 

 gain in the total nitrogen even when cultures were employed that had shown active 

 nitrogen assimilation in the laboratory. In no case was the condition of the plants 

 improved by the inoculation, but in a number of instances decided losses were 

 observed. These experiments were repeated several times in all, 60 pots and 3 dif- 

 ferent soils being employed. 



Some recent investigations in nitrogen assimilation by bacteria without 

 symbiosis, J. Vogel {Filhling's Landw. Ztg., 52 {1903), Nos. 5, pp. 178-180; 6, pp. 

 213-220). — The results of jjot and field tests of the so-called nitrogen assimilating 

 bacteria which do not live symbioticallj', particularly of Azotohacter chroococcum, are 

 reported. Comparisons are made of the yield, dry matter, and nitrogen content of 

 oats, mustard, and carrots grown in pots and in the field, the soil in each case having 

 received the same kind of complete fertilizer. The effects of inoculating with pure 

 cultures, adding grape sugar to the soils, and the presence of a comparatively large 

 amount of nitrate of soda, were compared. In the pot experiments with oats and 

 mustard increases were noted for the inoculated series, although those pots receiving 

 nitrate of soda gave the largest yields. When subjected to field conditions all inoc- 

 ulated plats gave less yields of dry matter and nitrogen than the uninoculated. In 

 this case the author states that inoculation seemed to have exerted an injurious 

 influence upon the product. 



Concerning the specific identity of the tubercle bacteria of the Legumi- 

 nosae and the agricultural importance of this subject, H. Buitlert {Ilablhchr. 

 Friedrichs-Univ. Halle, 1902, pp. 55; also Centbl. Bakt. u. Par., 2. Aht., 9 {1902), Nos. 

 5, pp. 148-153; G-7, pp. 226-240; 8, pp. 273-285).— A discussion is given of the rela- 

 tion of tubercle bacteria to leguminous plants and their function in the assimilation 

 of free atmospheric nitrogen. The author reviews tbe publications of a number of 

 investigators on this subject and gives the results of his studies in which he claims 

 that the bacteria of the root tubercles which are found on many leguminous plants 

 are all identical with Bacillus radicicola of Beijerinck. From the root tubercles of 

 some leguminous jilants there were found bacteria which seemed to be very much 

 specialized, but this specialization does not extend to differences that may be 

 regarded as specific. The usefulness of bacteria for inoculating purposes is demon- 

 strated, but it is thought to be confined within rather narrow limits. There does 

 not yet appear to be any pure culture preparation that is entirely trustworthy, and 

 on this account the author recommends recourse to soil inoculations to supply the 

 required organism. 



