AGRICULTUEAL BOTANY. 635 



It is concluded that autliocyaiiin is not formed from substances iu tlie cell sap, 

 but is the product of special organs termed cyauoplastids. These originate from 

 the protoplasm as a new product, being made up largely of timnin-like substance 

 inclosed in an envelope of unknown chemical composition, both envelope and 

 contents, however, being able to become sources of anthocyanin. Certain 

 external agencies seem able to hinder or prevent a transformation of the cyano- 

 plastid material into anthocyanin, this body remaining colorless. Each cyauo- 

 plastid seems to pass through a determinate cycle of development. When degen- 

 eration begins, the pigment formed therein is given up to the cell sap. Different 

 kinds of anthocyanin are found, giving various colors, which do not depend upon 

 the acidity of the cell sap to color a given pigment differently. 



On the presence of free hydrocyanic acid in plants, II, C. Ravenna and 

 V. Babini (Atti R. Acvad. Lincei, Rend. CI. Sci. Fis., Mat. e Nat., 5. set:, 21 

 {1912), I, No. 8, pp. 5.'fO-5JtJi).—By methods previously described (E. S. R., 24, 

 p. 229), the authors have made a study of the leaves of cherry laurel, peach, 

 sorghum, flax, and medlar, and have found that free hydrocyanic acid occurs in 

 appreciable quantity in all of them. 



The selective power of plants for dextrose and levulose, L. Lindet {Ann. 

 Inst. Nat. Agron., 2. scr., 10 (1911), No. 1, pp. .',9-68; abs. in Bot. Centbl., 119 

 {1912), No. 20, pp. Ji89, .'i90). — This article has been previously noted from other 

 sources (E. S. R., 25, p. 522). 



Potassium in relation to carbohydrate formation and decomposition, 

 J. Stoklasa {Ztschr. Landw. Vcrfiueli.sw. Ostcn:, 15 {1912), No. G, pp. 711- 

 736). — In pursuance of previous studies, noted elsewhere (E. S. R., 25, p. 522; 

 26, p. 225), on the physiological influences of certain metals, the author experi- 

 mented with the action of potassium on cells of several plants. He concluded 

 that potassium is generally indispensable to the building of carbohydrates, as 

 well as for their physiological combustion, also in the metabolic processes occur- 

 ring both in cells which lack and those which possess chlorophyll. 



The action of sulphurous acid on pollen, V. Sabachnikoff {Compt. Rend. 

 Soc. Biol. [Paris], 72 {1912), No. 5, pp. 191-193; abs. in Intemat. Inst. Agr. 

 [Rome], Bid. Bur. Agr. Intel, and Plant Diseases, 3 {1912), No. 4, pp. 10^9, 

 1050). — The author reports that in an atmosphere saturated with sulphurous 

 acid, pollen of the following plants was killed by an exposure of from 3 to 5 

 minutes: HeUcborus viridls, H. orlenialis, Hepatica triloba {Anemone hepatica), 

 Galunthus nivalis. Primula officinalis, Vinca minor, V. major, Convallarui 

 majalis, Narcissus pocticus, Caltha palustris, Cytisus laburnum, Viola tricolor. 

 Orchis maculata, Billbergia, Eranthis, and Crocus. 



Very small proportions of sulphurous acid (between 1 : 1,000 and 1 : 30,000 

 with exposures from 3 to 48 hours) do not as a rule kill the pollen or destroy 

 its germinating power, but the pollen tube grows abnormally, usually remaining 

 short, and taking an irregular form. This is said to have been noted in the 

 case of A. hepatica, Billbergia, H. orientalis, Vinca minor, Viola tricolor, P. 

 officinalis, Liliiim candidum. Petunia, and Pisum. The germinating property 

 of pollen remained unimpaired after exposure of from 1 to 48 hours to sul- 

 pharous acid with a concentration of 1 : 48,000, but this property was nsually 

 destroyed by a 3-hours' exposure to the concentration of 1 : 13,000, which condi- 

 tions of exposure may be considered as about the limits of safety for these 

 pollens. 



Injury to plants by vapors and dust from tarred roads, C. L. Gatin 

 {Ztschr. PflanzenkranJc., 22 {1912), No. 4, pp. 193-20.',).— This is a further 

 account of the author's investigations (E. S. R., 27, p. 333), stating that both 

 laboratory and garden studies support the conclusions that coal tar and its 

 products carried by air and dust to foliage are injurious to the plants ; that such 



