AGEICULTUEAL BOTANY. 223 



Radium and plant growth {Garil. Chron., 3. ser., 58 {1915), No. 1494, p. 102, 

 fig. 1). — It is stated that in experiments carried out by M. H. F. Suttou the 

 previous year, the germination of rape seed was accelerated when radio-active 

 ores were mixed with tlie soil, but that in two tests made by him during tlie 

 summer of 1915 with radium bromid tlie treated plants, wliich for about a 

 week outgi'ew the controls, showed a very unfavorable contrast therewith iu 

 about six weeks. This result is regarded as tending to show the noxious or 

 inhibiting effect of 7-rays on plant gi'owth. 



Freezing and frost killing of plants, H. Plahn-Appiani (Bl. Zuckerriiben- 

 lau, 22 (1915), No. 4, PP- S7-40). — Discussing the effects of differing degrees of 

 cold and rates of change as noted in several p-ants, the author holds that the 

 death point in plants due alone to cold as such is generally placed too high. 



Light and growth, I, A. H. Blaaitw (Ztschr. Bat., 6 (1914), No. 8, pp. 641-103, 

 figs. D). — The author, describing studies pursuant to those pi-eviously noted 

 (E. S. R., 23, p. 724), sums up the principal recent conclusions by stating that 

 a given light stimulus occasions a typical growth reaction in the plant cell 

 which follows certain definite laws, and that the phototropism of Phycemyces, 

 as noted in the experiments described, is the resultant of growth reaction to 

 light on different sides of the cell. 



The effects of photodynamically active coloring matters in solutions on 

 plant cells and tissues, J. Gicklhorn (Anz. K. Alcad. Yviss. [Yienna'\, Math. 

 Nat una. EL, No. 9 (1914), pp. 14O-I42; abs. in Bat. CcntbL, 126 (1914), No. 25, 

 pp. 662, 663). — These studies are claimed to have shown that plant cells, with 

 or without chlorophyll or anthocyanin, are subject in different degrees to char- 

 acteristic forms of injury on exposure to light and fluorescing coloring matters 

 • in solution, the injury being due not alone to light directly but also to the 

 heightening of toxic activities by light influence. High degrees of stimulation 

 check the streaming movement of the cell plasma, and continuance of the in- 

 jurious illumination stops it entirely. 



Chlorophyll is thought to have been shown in these experiments to act as 

 a sensibilizer in the process of carbon dioxid assimilation. 



Recent chemical investigations of the anthocyan pigments and their bear- 

 ing upon the production of these pigments in plants, A. E. Eveeest (Jour. 

 Genetics, 4 (1915), No. 4i PP- 361-361). — The author summarizes the more im- 

 portant points that have been investigated recently by himself (E. S. R., 31, 

 p. 62G) and others regarding the possible relationship between the red, purple, 

 and blue plant pigments (anthocyans) and the yellow plant pigments of the 

 flavone or flavonol class, and he points out their bearing upon some theories pre- 

 viously offered. 



A list is given of anthocyan pigments said to have been already isolated in a 

 chemically pure and crystalline condition with the claim that the structure of 

 each has now been definitely established. 



It is claimed that the anthocyans always occur as glucosids (anthocyanins) ; 

 that the same pigment (some anthocyans showing partial exceptions) may ex- 

 hibit a blue, purple, or red color, according as it exists as alkali salt, pure pig- 

 ment, or oxonium salt of some acid ; that the anthocyans may be obtained from 

 flavonols by reduction followed by spontaneous dehydration ; and that glucosids 

 of flavonols can pass, by reduction, to glucosid anthocyans (anthocyanins) with- 

 out intermediate hydrolysis. It is held that the molecular weights of the antho- 

 cyanidins are of the order of those of the flavonols. 



Hydrotropism in roots of Lupinus albus, H. D. Hookek, Je. (Ann. Bot. 

 [London], 29 (1915), No. II4, pp. 265-283) .—Work previously reported (E. S. R., 

 31, p. 728) has been followed up with a more detailed study of hydrotropism. 



