BOTANY. 739 



BOTAXY. 



The effect of sunshine on plants, X. Passerini (Bui. Soc. Bot. Ital., 190 J, pp. 

 13-34; f'^-"*- '" Jour. Rot/. 3f(a-o.s. Soc [London'\, 1902, Xo. 5, p. 574)- — The results of 

 growing 18 difft-rent species of plants in direct sunlight and in diffused light are 

 shown. By analyses the author determined the relative percentages of water, organic 

 matter, and ash of the 2 sets of plants. The highest gain was found in a gourd where 

 the plant grown in sunshine was 27 times heavier than the shaded plant. Next to 

 this in gains were barley and maize, the difference in each case being about 9 times 

 as great for the plants grown in the sunlight as in the shade. The greatest gain in 

 organic substani'e was shown by rape, barley, and pimpernel. The conclusions 

 drawn by the author are that in every case the plant exposed to direct sunlight is 

 heavier than the shaded plant, and that the failure of direct radiation limits the 

 growth of the plant and retards its vegetative phases, especially the inflorescence and 

 the comjilete development of the fruit. Plants grown in direct sunshine are much 

 greener than the shaded plants, and the shaded plants have a larger proportion of 

 water and less solid substance. The higher percentage of solids in the sun-grown 

 plants is chiefly due to the organic matter, the difference in the proportion of mineral 

 matter being less noticeable. 



Influence of X-rays on plants, H. Seckt {Ber. Deut. Bot. GeselL, W {1902), No. 

 2, pp. 87-9-1; (tf).^. in .Jour. Itoij. Microx. Soc [London^, 1902, No. 4, P- -#5). — The author 

 found that the exposure to X-rays distinctly favored the streaming movement of 

 protoplasm and the leaf movements of Mimosa and Oxalis. After from 15 to 45 

 mimites' exposure to these rays movements which before had been very slow became 

 quite rapid. When the tube of the apparatus experimented with was placed too 

 close to the object a greater or less tendency to jilasmolj^sis was observed. This the 

 author attributes to the harmful action of other electric waves. 



Electrical phenomena in plants, A. Tompa {Bot. Centbl., Beihefie, 12 {1902), pp. 

 99-l.)iJ, fiffs. .i; (ibx. iu Jour. Roij. Micros. Soc [Loudon'], 1902, No. 5, p. 574)- — There 

 was found to be no essential difference of intensity in manifestation of electric 

 polarization in living and dead seeds. The polarization currents in both dead and 

 living seeds may reach considerable intensity but are of small tension. Tlie amount, 

 intensity, and the direction of the current vary according to variations in the inter- 

 nal resistance of the seed. It is claimed that the question of living seeds may be 

 determined by what are termed lesion currents. A lesion current whose potential 

 exceeds 0.005 volt may be considered as a criterion of life in a seed. 



Electric response in plants under mechanical stimulus, J. C. Bose {Jour. 

 Linu. Soc [London], Bot., 35 {1902), pp. 275-304, figs. 25; abs. in Jour. Roij. Micros. 

 Soc [Jjondon], 1902, No. 5, pp. 574, 575). — The object of the author's experiments 

 was to prove that plants and their different organs respond to electric stinmli in the 

 same way that animal tissue responds, indicating that vital phenomena are identical 

 in the animal and plant kingdoms. The responses are held to be physiological, 

 since whatever inliuences the jihysiological activity of the plant also tends to increase 

 or diminish the electric response. The author emphasizes the importance of this 

 unity between plants and animals; and owing to the simpler conditions which obtain 

 in plant life, the electro-physiological investigations in plants may be found to throw 

 nuich light on this subject. 



Concerning' the respiration of injured leaves, X. Dorofeiew {Ber. Deut. Bot. 

 GeselL, 20 {1902), No. 7, pp. 396-402). — By separating leaves from the jilants bearing 

 them and placing them under various conditions the author studied the effect of 

 such separation and injury upon the respiration of the leaves. It was found that 

 the carbohj'drates present in the leaves influence their respiration to an important 

 degree. If the carbohydrates are abundant there is but a slight increase in the 

 respiration due to the wounding, while if the amount is small the respiration is 

 greatly accelerated. This was found to be true both for green and etiolated plants. 



