AGRICULTURAL BOTANY. 29 



those from ordinary sunlight, or else tend toward destruction of the vitality 

 of the superficial leaf cells, resulting in discoloration and death of the foliage 

 without, however, injuring the rest of the plant or decreasing its power of 

 foliage reproduction. These results largely confirm those reported by Maqueune 

 and Demoussy (E. S. R., 22, p. 436). Plasmolytic tests show that in some 

 cases at least the upper surface of the stomatal guard cells is most readily 

 affected. The discoloration of the leaves is explained by the chemical changes 

 in the dead protoplasm. Flower petals are more quickly altered than are leaves 

 by the ultraviolet rays, both flowers and leaves of indoor plants being more 

 readily affected than are those of outdoor plants, and the species being more 

 significant in this connection than the flower color. 



It is regarded as established that ultraviolet rays exert a great influence on 

 the development of chlorophyll-forming organs as well as upon the activity of 

 these organs, but that prolonged action of such rays disturbs profoundly the 

 life processes in the leaf cells. 



The relation of chlorophyll formation to light wave length, A. Schmidt 

 (Beitr. Biol. Pflanz., 12 {191.',), .A'o. 2, pp. 269-29-',, pis. 2).— Noting briefly 

 studies of other authors as cited on the relations of light, chlorophyll, and as- 

 similation, the author gives an account of his own investigations, employing 

 Zea mays, in regard to the influence of different wave lengths of light on the 

 synthesis of chlorophyll. 



The results are said to present analogies to those noted by Kniep and Minder 

 (B. S. R., 22, p. 229) and by Lubimenko (E. S. R., 25, p. 431) regarding the 

 assimilation of carbon dioxid, inasmuch as for chlorophyll formation, as well as 

 for assimilation, there are two maxima, the blue rays possessing a greater 

 significance than was formerly ascribed to them in this regard. 



A bibliography is appended. 



A simple apparatus for the study of phototropic responses in seedlings, 

 G. X. IIoFFEB {Proc. Ind. Acad. Sci., 1913, pp. 93-96, figs. 4).— This apparatus, 

 made up chiefiy of the microscope with a micrometer eyepiece attached to the 

 side of its carrying case used as a dark chamber, is employed to observe minute 

 responses of seedlings and fungi to filtered solar rays. 



Irritability as related to plasmatic conditions, A. Heilbeonn (Jaliri. Wiss. 

 Bot. [Pringsheim], 54 {1914), No. 3, pp. 351-^90, fig. l).—ln a study of Vicia 

 faia and Arena sativa the author found the viscosity of living substance to 

 have a minimum of 9 times and an average of 24 times that of water. It is 

 concluded also that cell plasma opposes not only chemical but physical proper- 

 ties to influences tending to limit motion therein. 



A bibliography is given. 



Transpiration of Silphium laciniatum, L. A. Giddings (Plant World, It 

 (1914), No. 11, pp. 309-328, figs. 10). — This is a detailed account of experiments 

 already reported (E. S. R., 30, p. 726). 



The physiology of germination, G. Mijlleb {Jahrh. Wiss. Bot. [PringsTieim'i, 

 54 {1914), No. 4, pp. 529-644. figs. 35).— The author states, among other find- 

 ings, that the causes of pressure noted as tending to burst the seed coats are 

 imbibed water and growth of endosperm, cotyledons, or rootlets. The struc- 

 tural arrangements favoring escape of the embryo are described as belonging to 

 five different types. Pressures found to develop during changes in the cotyle- 

 dons and endosperm are given. The resistance of dehiscence lines in seed coats 

 is said to be lessened by the presence of water. 



A bibliography is appended. 



The germination of seeds of Arisaema, F. L. Pickett (Proc. Ind. Acad. Set., 

 1913, pp. 125-128, figs. 6). — Seeds of A. triphyllum gave a high jjercentage of 

 germination, and it is noted that some germinate blindly, that is, the embryo 



