FIELD CROPS. 329 



Carbon dioxid is claimed to sbow stimulative effects at low partial pressures, 

 these rising to a maximum with increasing pressures and then declining to 

 inhibition with higher pressures of carbon dioxid, at least iu case of Brassica 

 alba and Hordeum vulgare germinated in the dark. Kapidly deteriorating seeds 

 (as in case of Hevea brasiliensis) in the confined carbon dioxid of their own 

 natural respiration showed a marked prolongation of vitality, this being far 

 in excess of that shown by such seeds as ordinarily packed for shipment. 



It is claimed that in general the arrested development of moist maturing or 

 resting seeds is primarily a phase of carbon dioxid narcosis due to a partial 

 pressure of that gas in the tissues of the embryo, and that the final germination 

 is related to a lowering of the inhibitory partial pressure. 



Observations on the development and germination of the seed in certain 

 Polygonaceee, E. F. Woodcock (Amcr. Jour. Bot., 1 (1914), No. 9, pp. 454-476, 

 pis. 4)- — The author describes the morphology of the seed of a number of 

 species of plants belonging to the family Polygonacese, after which he gives an 

 account of investigations on their germination. 



It was found that the germination of Rumex crispus, Fagopyrum esculcntum, 

 PolygoncUa articulata, and Polygonum scandens shows that the aleuroue layer 

 has pi'esumably a digestive function, secreting a ferment which converts the 

 insoluble starch of the endosperm into a foi-m available for the germinating 

 embryo. The cells of the layer become much enlarged, and in Kumex, Poly- 

 gonella, and Polygonum this inci'ease in size of the aleuroue layer causes the 

 micropylar portion to appear outside the seed coats. In Rumex and Fagopyrum, 

 the absorbed carbohydrate is temporarily reconverted into starch in the tissues 

 of the germinating embryo, the cotyledons being the principal storage organs. 



The significance of radio-activity in physiology, J. Stoklasa (Ccntbl. Bakt. 

 [etc.], 2. Abt., 40 {1914), No. 11-13, pp. 266-280).— This is mainly a synthetic 

 review of the results of studies continued by the author and several collaborators 

 during the past seven years, some of which have already been noted (B. S. R., 

 28, p. 731 ; 29, p. 130 ; 30, p. 524). The leading motive of these studies is to dis- 

 cover in what ways radio-activity is related to metabolic processes in plants 

 with or without chlorophyll, that is, bacteria, yeasts, and higher plants (includ- 

 ing germination, growth, and respiration of these last). The conclusions 

 reached are presented in considerable detail. 



Photosynthesis in submerged land plants, H. Y. Heimburger (Proc. Ind. 

 Acad. Sci., 1912, pp. 95-98). — According to the author a number of land plants 

 are able to carry on photosynthesis when submerged in water, Melilotus alba 

 and Ncpcta catana showing considerable evolution of gas when so submerged. A 

 number of other species are noted as able to carry on this process under abnor- 

 mal conditions, but with less evolution of gas than in the species above 

 mentioned. 



FIELD CROPS. 



A biological and statistical analysis of the vegetation of a typical wild 

 hay meadow, A. B. Stout {Trans. Wis. Acad, Sci., Arts, and Letters, 17 {1913), 

 pt. 1, pp. 405-470, pis. 6). — In this article the author reviews investigations of 

 other workers along this line, and gives the results of his study of the marsh 

 formations of the region about the city of Madison, Wis., by analysis of the 

 flora by statistical methods with the aim of obtaining the numerical relations 

 and the relative importance of the various species as they are grouped in such 

 association. 



The plants other than Eleocharis species in every other foot of a 4-in. strip 

 2,300 ft. in length, were counted, and a list of species growing on this strip is 



