AGRICULTURAL BOTANY. 629 



as a heightened content of carbon dioxul considerably accelerated and increased 

 development in tlu- plants employed. 



The effects of high temperatures on leguminous seeds, F. NEunERGEB 

 {Kiscrlel. Kozlcm., 17 (1914), No. J, jjp. 121-170).— The author exposed seeds 

 of several leguminous plants in dry air at temperatures of 50 to 130° C. for i 

 to 6 hours and in water at 45 to 100° C. for i to 2 hours, and then tested them 

 for germinability under favorable conditions. 



It was found that in general the injurious effects of high temperature were 

 increased by its elevation and its duration. Decrease of water content in seeds 

 by artificial drying increased progressively the power of resistance to heat in 

 dry air. This, however, ceased at 130° C, even for short exposures. 



Water at a temperature above the maximum point for germination remained 

 harmless to seeds therein only until the germination changes were started. 

 Resistance varied even within species and is considered as largely an indi- 

 vidual character. High temperature is thought to break down the enzyms con- 

 nectetl with activity of germination. 



A bibliography is given. 



Death of young plants from heat, L. Schusteh (Natunc. Ztschr. Foist u. 

 Landw., 12 {li>14). No. 8, pp. 377-379, figs. 2). — Noting accounts of heat injury 

 by von Tubeuf (E. S. R., 31, p. 343) and by Miinch (E. S. R., 31, p. 34S), the 

 author describes the effects of heat combined with dryness of the soil on plant- 

 lets of Cedrela odorata, Baphia kirlcii, and Afzeia euanzensis in the neighbor- 

 hood of Morogoro, German East Africa. 



External and internal phases of the action of attenuated acid gases and 

 smoke on plants, H. Wislicenus (.1/?^^ K. Sachs. Forstl. Vcrsuchsanst. 

 Tharandt, 1 (1914), J^o. 3, jyp. S5-175, pis. 4, figs, ifl).— This is a somewhat 

 extended account of the repetition of former work under improved conditions 

 and of later work (E. S. R., 10, pp. 531, G 14 ; 32, p. 524), bearing upon the 

 effects of atmospheric pollution with smoke and gases from industrial plants, 

 particularly in high attenuation, upon development and functioning in plants. 



It is stated that highly attenuated sulphuric acid is markedly injurious to 

 plants only when the leaves or needles are assimilating and in proportion to the 

 intensity of that activity, this acid being then poisonous and a delicate indicator 

 of photosyutbetic activity. Light intensity and assimilative activity are the 

 principal conditions, but others are discussed as modifying factors. 



Forest injury from coal smoke, C. Baltz (Ztschr. Forst u. Jagdw., 46 (1914), 

 No. 3, pp. 15S-174)- — Summing up a discussion of work reported by Wieler 

 (E. S. R., 31, pp. 322, 521) and others, the author states that smoke injury to 

 forest growth near furnaces is due largely to the direct action of the acids 

 resulting from the oxidation of sulphur dioxid. 



The degree of injury depends largely upon the situation and configuration 

 of the area affected. It is favored by the melting of snow, also by fog or slow 

 falling rains, which absorb the acid and give it up to the foliage. The effect is 

 greater in case of the younger parts. Conifers are more sensitive than de- 

 ciduous trees. 



Good cultural conditions are considered the best means of protection against 

 a tendency to injury through the soil. 



Physiological characters of plants, their variability and their relation to 

 the theory of evolution, S. Ivanow (Bot. Centhh, Beihcfte, 82 (1914), 1- ^^t.. 

 No. 1, pp. 66-SO). — From a study of the characters, particularly oil production, 

 of several series of species, the author concludes that plant characters fall intc 

 two categories, namely, morphological (which depend more upon externa] 

 conditions and by modification form new species) and physiological (consisting 



