632 EXPERIMENT STATION RECORD. [Vol.35 



sulphate in Europe and North America. No figures are given relating to the 

 production of potash salts in Germany, the tables showing only those amounts 

 deliveped for internal trade and export as fixed by the law of 1910. 



The wholesale prices of raw phosphate remained practically unchanged in the 

 United States during the seven months ended with February, 1915 (prices are 

 not given for superphosphates). Prices of potash salts were prohibitive from 

 the standpoint of their use as fertilizers during the half year ended with Jan- 

 uary, 1916. There was a steady increase in the price of sodium nitrate during 

 the same period. Prices of ammonium sulphate fluctuated, but were substan- 

 tially the same at the end as at the beginning of the half year. 



A bibliography of 445 references to recent literature on the subject of fer- 

 tilizers is appended. 



AGRICULTURAL BOTANY. 



Annual periodicity in plants, G. I.akon (Naturw. Ztschr. Worst u. Landw., 

 13 (1915), No. 2-3, pp. 85-101). — From investigations discussed the author con- 

 cludes that an inherent annual periodicity in woody plants does not exist as 

 such, but that this, as seen in nature, is the result rather of external 

 influences on the tree. The plant is claimed to have the capability to grow 

 continuously under certain conditions, or under other conditions to experience 

 a resting period. 



Rhythmic alternation of growth and rest in plants, G. Lakon (Biol. Centbl., 

 35 (1915), No. 10, pp. 401-471). — The article above noted has been followed up 

 with a more extended discussion and bibliography. The evidence is claimed 

 to support the conclusion that the development of periodicity, like that of the 

 plant itself, is dependent principally upon the occurrence of external condi- 

 tions favorable thereto. 



Energ'y transformations during the germination of wheat grains, Lucie C. 

 DoYER (K. Akad. Wcte^i^ch. Amsterdam, Proc. Sect. Sci., 11 (1914), pt. 1, pp. 

 62-70). — From investigations on germinating wheat, the author has concluded 

 that the loss of energy and evolution of heat both show a great increase dur- 

 ing the germination of wheat grains, especially about the third day. The evolu- 

 tion of heat depends greatly on the surrounding temperature, the optimum be- 

 ing about 35° C. (95° F.). The total loss of energy during germination at 

 20° exceeds the loss of energy by evolution of heat at the same temperature. 



The influence of frost and light on the germination of seeds, W. Kinzel 

 (Naturio. Ztschr. Forst u. Landw., 13 (1915), No. 10, pp. 433-468) .—Ijater 

 results are given of experimentation previously noted (E. S. R., 33, p. 343) 

 testing influences bearing on germination, particularly the effect of frost and 

 light as shown by representatives of a large number of plant families, together 

 with a bibliography of the subject. 



Germination as related to illumination, E. Lehmann (Ztschr. Bot., 7 (1915), 

 No. 9, pp. 560-580). — The author has followed up the contribution of Gassner 

 (E. S. R., 35, p. 524), with a critical review of recent literature on the relation 

 of light to germination. Some experimental data in tabular form obtained re- 

 cently by Ottenwiilder in connection with the author are included. 



On the mutual influence of phototropic and geotropic reactions in plants, 

 C. E. B. Beemekamp (K. Akad. Wetensch. Amsterdam, Versl. Wis en Natuurk. 

 Afdeel., 23 (1914-15), pt. 2, pp. 1241-1255; also in ditto, Proc. Sect. Sci., 17 

 (1914-15), pt. 2, pp. 1278-1291).— The tests here described refer to the summa- 

 tion of phototropic and geotropic curvatures, changes in the phototropic and 

 geotropic reactions under the influence of light, and changes in the geotropic 

 and phototropic reactions under the influence of gravity. 



