491 Stoffaufnahme. Allgemeines 305 



sodium nitrates, and especially calcium nitrate, were used with Azotobacter, 

 the coloration increasing with the concentration of the salt. This effect was 

 more marked in Azotobacter strains which produce little or no pigment in the 

 absenee of nitrates. 5. All three nitrates studied caused an increase in the 

 number and size of volutin bodies in Azotobacter cells. From all appearances 

 these salts also tended to hasten the development of these bodies. 6. The number 

 of Bacillus radicicola in sterilized soil was increased by the addition of small 

 quantities, of potassium, sodium, ammonium, and calcium nitrates. This increase 

 was not so marked as in the Azotobacter cultures. B. radicicola appeared to be 

 much more resistant to higher concenlrations of nitrates than Azotobacter. 

 7. B. radicicola under aerobic conditions did not reduce nitrates in Solution to 

 nitrite, ammonia, or elemental nitrogen. The presence of nitrates did not 

 materially influence the small amount of atmospheric nitrogen fixed under Ihese 

 conditions. 8. When grown on agar films, B. radicicola fixed a small amount 

 of nitrogen, varying from 0,15 to 0,43 mg of nitrogen in 100 ccm of the medium. 

 The addition of various amounts of potassium, sodium, and calcium nitrates 

 increased to a slight extent the amount of nitrogen assimilated. 9. In liquid 

 cultures all three nitrates caused a large increase in the amount of gum obtained 

 by precipatation with acetone. 10. The presence of large amounts of potassium, 

 sodium, and calcium nitrates proved detrimental to the formation of nodules on 

 alfalfa. B. radicicola did not appear to lose its infecting power when grown 

 im media containing varying amounts of sodium and calcium nitrates. Alfalfa 

 seedlings grown in the presence of large amounts of nitrate did not produce 

 nodules when inoculated with a viable culture of B. radicicola. Nitrates in soil 

 cultures prevented the re-formation of nodules once removed and also cause a 

 decrease in the number of nodules already present." 



319. Hirsch, P. Die Einwirkung von Mikroorganismen 

 auf die Eiweißkörper. (Berlin, Gebr. Borntraeger, 1918, 255 pp., 

 4 Tai.) — Ref. in Bot, Ctrbl. 140, 1919, p. 365—366. 



320. Johnson, Erling. Dieyandiamidets indvirkning p a a 



planteveksten. [Einwirkung des Dicyandiamids auf das Pflanzen- 

 wachstum.] (Nordisk Jordbrugsforskning I, 1919, p. 267 — 272.) — Durch um- 

 fassende Vegetationsversuche mit Hafer wurde versucht, die Frage zu ent- 

 scheiden, ob eine Verunreinigung des als Düngemittel benutzten Cyanamids 

 mit Dicyandiamid für das Pflanzenwachstum schädlich ist. Bei größeren Kon- 

 zentrationen von Dicyanamid war die Ernte etwas herabgesetzt, bei kleineren 

 Konzentrationen war dagegen keine Giftwirkung zu konstatieren. In Gegen- 

 wart von anderen leichter assimilierbaren N-Verbindungen treten die schäd- 

 lichen Wirkungen des Dicyandiamids ganz zurück. C o 1 1 a n d e r. 



321. Johnson, E. Dieyandiamidets indvirkning p a a 

 planteveksten. (Nordisk Jordbrugsforskning II, 1920, p. 130 — 135.) — 

 Erwiderung auf die Einwände Bondorffs (Nord. Jordbrugsf. I, 1919, 359 — 361) 

 gegen die vorangehende Arbeit. C o 1 1 a n d e r. 



322. Jovino, S. Osservazioni s u 1 1 ' a r i d o c o 1 1 u r a i t a 1 i a n a. 

 (Le Staz. sper. agrarie ital. 52, 1919, p. 69—121, 125—192.) 



A. Borntraeger. 



323. Kelley, W. P. Effect ofnitrifyingbacteriaon the So- 

 lu b i 1 i t y o f tricalcium phosphate. ( Journ. Agric. Res. 12, 1918, 

 p. 671—683.) 



Botanischer Jahresbericht XL VIII (1920) 2. Abt. [Gedruckt 3. 11. 30] 20 



