164 SOIL SCIENCE [BoT. Absts., Vol. IX, 



tonus, which does not depend on the fertilization of the flower. Fertilization is related to 

 the reaction only in that it induces renewed growth. The reactions are geotropically positive 

 and phototropically negative, they are dorsiventral, and dissimilar curvatures result from the 

 stimulus of gravity or light alone. The normal curvature is the resultant of the geotropic and 

 the phototropic reactions. The striking over-curvature is due to the fact that the post- 

 floral growth progresses from the free end to the fixed base and the curvature does not displace 

 the zone which is still capable of growth and reaction from the position of stimulation. The 

 counter reaction is slight because the growth period is short and the reaction time very long. — 

 R. M. Holman. 



1041. ZoLLiKOFEB, Clara. Ucber die tropistische Wirkung von totem Licht auf Dun- 

 kelpflanzen von Avena sativa. [Tropic action of red light on etiolated plants of Avena sativa.] 

 Verslag. K. Akad. Wetenschappen Amsterdam 29: 551-558. 1 fig. 1920. — Experiments were 

 conducted in a darkroom under the influence of a 100 candle-power light, surrounded by very 

 dark ruby glass which was spectroscopically tested, the room having a constant temperature 

 of 22.5°C. and a moisture content of 55 to 60 per cent. All reactions showed a remarkable 

 uniformity at any definite light intensity. The lowest light intensity at which any observ- 

 able phototropic action occurred was between 15 and 30 M. C. S. — /. C Th. Uphof. 



RADIANT ENERGY RELATIONS 



1042. DisHOEK, A. F. C. van. Gevoeligheid voor licht van + en — stammen van Phycomy- 

 ces nitens. [Light sensitiveness of "plus" and "minus" strains of Phycomyces nitens.] 

 Verslag. K. Akad. Wetenschappen Amsterdam 29: 667-669. 1920. — In phototropic experiments 

 with Phycomyces nitens the various strains do not give the same results. With one-sided 

 illumination the sporophores of the minus strains were strongly directed toward the light, the 

 plus strain slightly. Other observations as to light sensitiveness are given. — J. C. Th. 

 Uphof. 



1043. Meyer, Fritz J. Die Licht Physiologie der Pfianzen. [The light physiology of 

 plants.] Naturwissenschaften 8: 842-851. 5 fig. 1920. — This is a critical presentation of 

 the results of important papers of recent years dealing with (a) light and germination, (b) 

 light and growth, (c) light and assimilation, (d) the lethal effect of ultraviolet rays, and (e) 

 light and plant movements. — 0. L. Clark, 



TOXIC AGENTS 



1044. Atwood, W. M. Physiological studies of the effects of formaldehyde on wheat. 

 [Abstract.] Phytopathology 11: 103. 1921. 



1045. Seeliger, Rud. tJber einige physiologische Wirkungen des Osmium tetroxyds. 

 [Some physiological effects of osmium tetroxide.] Ber. Deutsch. Bot. Ges. 38 : 176-184. 1920. — 

 Grains of wheat kept for 8 hours in ^ to j per cent solutions of osmium tetroxide sub- 

 sequently showed 100 per cent germination. Some germinated even after similar treatment 

 with 1 per cent solution. The harmful effect of the tetroxide was evident in the slower ger- 

 mination of the wheat, in the slower growth of the seedlings, and in a permanent dwarfing 

 of the plants. — R. M. Holman. 



SOIL SCIENCE 



J. J. Skinner, Editor 

 F. M. Schertz, Assistant Editor 



(See also in this issue Entries 585, 588, 589, 590, 595, 596, 604, 605, 606, 616, 620, 638, 682, 



790, 820, 1030) 



GENERAL 



1046. BouYoucos, George. The amount of unfree water in soils at different moisture 

 contents. Soil Sci. 11: 255-259. 1921. — By the use of the dilatometer the amount of unfree 



