AGRICULTURAL BOTANY. 427 



fereut parts of the plant and the period of growth. The nitrogen precipitated 

 hy phosphotuugstic acid was determined for different parts of the plant, and 

 other forms of soluble nitrogen than those precipitated by phosphotungstic acid 

 and sodium hydroxid were found to occur. Fixation was found to take place 

 at a very early period in the growth of the seedling, sometimes within 14 days, 

 and in some cases was quite rapid, especially with cowpeas. Plants grown 

 under the conditions of these experiments were found to contain no ammonia, 

 nitrites, or nitrates, as measured by the most accurate chemical methods. 



The protective action, ag-ainst magnesium carbonate, of calcium carbonate 

 for Azotobacter chroococcum, C. B. Lipman and P. S. Buegess (Jour. Agr. Sci. 

 [England], 6 (1914), No. Jf, pp. 484-J,9S).— The authors have studied the effects, 

 separately and together, of calcium carbonate and magnesium carbonate on 

 nitrogen fixation by A. chroococcum. They state that while the first is stimu- 

 lating and never toxic to this organism in concentrations up to 2 per cent in 

 mannite solution cultures, the second is sharply toxic thereto in concentra- 

 tions above 0.1 to 0.2 per cent in such cultures. While the calcium salt in soil 

 cultures is without effect when present in amounts up to 1.4 per cent of dry 

 soil weight, wlien it becomes slightly toxic in Anaheim sandy soil, the magne- 

 sium is even more toxic in such soil cultures than in solution cultures. The 

 toxic efi'ect of magnesium carbonate is ascribed to the magnesium ion. 



Calcium carbonate exercises a protective influence in solution cultures and 

 soil cultures for A. chroococcum against the toxic properties of magnesium 

 carbonate. The optimum ratios found of these two components are 6 : 1 and 

 15:1 in these two media, respectively, when the absolute values of the two 

 components employed are 1.25 and 0.2 per cent in solution and 1.5 and 0.1 per 

 cent in soil cultures. 



Study of the gas exchange and the variation of sugars and glucosids 

 during the course of the formation of anthocyanic pigments in the flowers 

 of Cobaea scandens, E. Rose (Rev. G4n. Bot., 26 (1914), No. 307, pp. 257-210).— 

 A brief account of this investigation has been previously noted (E. S. R., 31, 

 p. 427). 



Investigations on the penetration of violet and ultraviolet rays in various 

 plant organs, P. A. Dangeaed (Bui. Soc. Bot. France, 61 (Wl/f), No. 1-3, pp. 

 99-103). — The author reports investigations on the penetration of violet and 

 ultraviolet rays through the tissues of various plant organs. 



It was found that different species of plants behaved quite differently toward 

 the different wave lengths of the lights, some of the wave lengths readily 

 penetrating leaves, while others were greatly reduced or entirely prevented 

 from passing through. Hairy leaves retarded penetration more than glaucous 

 or smooth ones. 



The action of Salton Sea water on vegetable tissues, M. A. Bbannon (Car- 

 negie Inst. Washington Pulj. 193 (1914), PP- 71-78, pis. 3). — ^This is a fuller 

 report than that already noted (E. S. R., 30, p. 431), on the anatomical study 

 of dead plants submerged for one to five years in the Salton Sea, on the bac- 

 terial study of the water, and on the processes engendered in fresh woods kept 

 in such waters at room temperature. 



Woody plants submerged in the Salton Sea were decorticated in about one 

 year. Fresh woods kept in Salton water showed a breaking down in the zone 

 of meristematic cells, but sterilized specimens kept in such water did not 

 decorticate during ten months. 



An organism belonging to the Amylobacter group was isolated, which pro- 

 duces an enzym capable of hydrolyzing pectins. 



Woods emerging annually from 1907 to 1911 showed no breaking down of 

 cell walls in any portion. It is believed that the action of this water on 



