348 W. Wendler: Chemische Physiologie 1917— 1919 |^2 



590. Zakrzewski. Fabrikmäßige Herstellung von Ei w e i ß 

 durch H e f e z ü c h t u n g. (Schrift. Naturf. Ges. Danzig, N. F. 14, 1917, 

 p. 49—57.) — Ref. in Bot. Ctrbl. 140, 1919, p. 128. — Siehe auch „Pilze 1917", 

 Nr. 821. 



591. Zeller, Sandford M. Studies in t li e physiology o f the 

 fungi. III. Physical properties o f w o o d in relation t o 

 decay induced by Lenziies saepiaria Fries. (Ann. Missouri Bot. 

 (Lud. 4, 1917, p. 93—164, mit Taf. 9—13.) 



592. Ziegenspeck, Hermann. Amyloid in jugendlichen 

 Pflanzenorganen als vermutliches Zwischen p r o d u k t 

 bei der Bildung von W a n d k o h 1 e n h y d rate n. (Ber. D. Bot. 

 Ges. 37. 1919, p. 237 — 278.) — In einer großen Zahl von Pflanzen konnte Verf. 

 durch Jodjodkalilösung eine Blaufärbung des Siebteiles erzielen. Der Deutung 

 dieser Erscheinung wird eine kurze chemische Betrachtung vorausgeschickt. 

 — Siehe auch Nr. 141, 194, 611. 



VIII. Atmung 



593. Bailey, C. H. and Gurjar, A. M. Respiration o f s t o r e d 

 wheat. (Journ. Agric. Res. 12, 1918, p. 6S5 — 713.) — Conclusions: „1. De- 

 ductions from these investigations support the findings of earlier investigators 

 that spontaneous heating in damp grain is occisioned by the biological oxidation 

 of dextrose and similar sugars chiefly in the germ or embryo of the kernel. 

 2. Moisture is one of the determining factors in respiration. It establishes the 

 comparative rate of diffusion between the several kernel structures. Any gain 

 in the moisture content of the kernel accordingly increases the rate of diffusion 

 and, simultaneously, the rate of respiration. The increase is gradual and 

 fairly uniform until the moisture exceeds 14,5 per cent, in the case of plump 

 spring wheat, when it is markedly accelerated. 3. Density of the wheat kernel 

 generally parallels the gluten content. Gluten possesses the property of imbibling 

 more water than starch, and thus varying percentages of gluten result in 

 varying degrees of viscosity at the same moisture content. The relative 

 viscosity affects the rate of diffusion and this in turn directly affects the rate 

 of respiration. The soft, starchy wheats thus respire more rapidly than hard, 

 vitreous wheats containing the same percentage of moisture. 4. Plumpness of 

 the wheat kernel affects the rate of respiration, as shown by contrasting 

 plump and shriveled grain. The shriveled wheat respired two to three times 

 as much as did the plump wheat at moisture Contents above 14 per cent. At 

 percentages of moisture below 14 per cent the difference is not very marked. 

 The high acceleration of respiration in shriveled wheat containing more than 

 14 per cent of moisture is attributed to the higher ratio of germ to endosperm 

 and hence the larger percentage of enzym to Substrate as compared with plump 

 wheat. 5. The period of dampness — that is, the length of time the excess 

 moisture has been present in the wheat — bears a relation to the rate of 

 respiration. This is shown by comparing the respiration of freshly dampened 

 wheat with that of naturally damp grain and with grain that had been dampened 

 and stored for varying lengths of time. The curve of respiration diverges from 

 that of freshly dampened wheat when the moisture content exceeds 12 per cent, 

 and tlii- divergence is more marked after 13 per cent of moisture is reached. 

 In the case of wheat dampened and stored, the quantiiy of carbon dioxid 



