304 W. Wendler: Chemische Physiologie 1917— 1919 [48 



and transference of the elenients in the plants. — Attention is called to the 

 bearing of these results on the method of applying fertilizers. — The results 

 obtained agree with Mitscherlich's formulation of the law of 

 rainimum." 



311. Greve, Gustav. Die künstlichen Stickstoffdünge- 

 mittel, ihre Herstellung und ihr Verhalten zu Boden 

 u n d P f 1 a n z e. Berlin (Paul Parey) 1920. 



312. Gurlitt, L. Über den Einfluß der Konzentration 

 der Nährlösung auf einige Pflanzen. (Beih. Bot. Ctrbl. 35, 1., 

 1918, p. 279—341, mit 32 Texfig.) — Ref. in Bot. Ctrbl. 141, 1919, p. 19—20. 



313. Hanoe, R. T. An attempt to modify the germ plasm 

 o f Oenothera t h r o u g h the g e r m i n a t i n g s e e d. (Amer. Naturalist 51, 

 1917, p. 567—572.) — Ref. in Bot. Ctrbl. 137, 1918, p. 34. 



314. Härder, R„ Ernährungsphysiologische Unter- 

 suchungen anCyanophyceen, hauptsächlich dem endo- 

 phy tischen Nostoc punctiforme. (Ztschr. f. Bot. 9, 1917, p. 145 — 242, mit 

 71 Fig.) — Ref. in Bot. Ctrbl. 141, 1919, p. 134—136. 



315. Hartmann, M. Über die dauernde, rein agame Züch- 

 tung von Eudorina elegans und ihre Bedeutung für das Be- 

 fruchtungs- und Jodproblem. (Sitzungsber. Akad. Wiss. Berlin, 

 Phys.-Math. Kl. 52, 1918, 760—776.) 



316. Heinricher, E. Zur Physiologie der schmarotzenden 

 Rhinantheen, besonders der halbparasitischen. (Die 

 Natunvissensch. 5, 1917, p. 113—119.) — Ref. in Bot. Ctrbl. 141, 1919, p. 214 

 bis 216. 



317. Heise, R. Über dieEinwir k u n g v o n z o n auf M i k r o - 

 Organismen und künstliche Nährsubstrate, als Beitrag 

 zur Kenntnis der z o n w i r k u n g in F 1 e i s c h kühl h alle n. 

 2. M i 1 1. Die Einwirkung von Ozo n a u f künstliche N ä h r - 

 b ö d e n und auf verschiedene Bakterien, Hefen und 

 Schimmelpilze. (Arb. Kaiseil. Gesundheitsamt 50, 1917, Heft 4.) — 

 Ref. in Ctrbl. Biochem. Biophysik 19, 1918, p. 370—371. 



318. Hills, T. L. Influenae o f nitrates onnitrogen-assi- 

 iii i 1 a t i n g bacteri a. (Journ. Agric. Res. 12, 1918, p. 183—230.) — Sum- 

 mary: „1. Small quantities of potassium, sodium, and calcium nitrates caused 

 a great increase in the number of Azotobacter in sterilized soil. Ammonium 

 nitrate in the same quantities caused a less marked increase. Higher concen- 

 trations were not so favorable to the growth of the organism. 2. Potassium 

 and sodium nitrates in the concentrations studied caused an increase in the 

 amount of nitrogen assimilated by Azotobacter on agar films. Calcium nitrate 

 in the same amounts brought about a decrease in the amount of nitrogen fixed 

 to a point even below that representing the amount assimilated in the absence of 

 nitrates. In soil cultures nitrates of sodium and calcium caused an increase 

 in total nitrogen, whicli was more marked in the unsterilized cultures than in 

 those cultures sterilized and inoculated with a pure culture of Azotobacter. 

 However, the increase in total nitrogen is not commensurate with the increase 

 in the number of Azotobacter noted under the same conditions. 3. Under aerobic 

 eonditions Azotobacter in liquid cultures reduced nitrate to nitrate, but not to 

 ammonia. More atmospheric nitrogen was assimilated in the presence of nitrate 

 than in the absence of this salt. 4. Pigmentation occurred when potassium and 



