AGEICTJLTURAX BOTANY. 219 



In 1912 similar experiments were carried on wliicli confirmed the previous 

 results. In addition reports are made on other mineral constituents. Only 

 about one-fifth of the lime was removed from the leaves by exosmosis and 

 about 40 per cent of the magnesiia. Sulphuric acid was eliminated to a large 

 degree, the combinations which it forms with minerals being such that they 

 were readily soluble after the death of the leaves. 



Experimental study of the effect of some nitrogenous soil constituents 

 on growth. — Nucleic acid and its decomposition products, O. Schreineb and 

 J. J. Skinner (Plant World, 16 (1913), No. 2, pp. 1,5-60, fig. /)•— The conclu- 

 sions presented are essentially tliose previously noted from another source 

 (E. S. R., 28, p. 324). 



A note on the significance of sugar in the tubers of Solanum tuberosum, 

 O. Butler (Bui. Torrey Bot. Club, 40 (1913), No. 3, pp. 110-118, pi. 1, figs. 2).— 

 A study of the sugar which accumulates in the tubers of potatoes during the 

 rest period, as influenced by temperature and oxygen supply, is reported upon. 



The author considers the accumulation of sugar, so far as germination is 

 concerned, as having no particular physiological significance. Potatoes were 

 found to contain little or no sugar near their apices and sometimes nearly as 

 much in their middle as in their basal portions, although frequently the 

 greatest amount was foimd in the base of the tuber. From his experiments 

 he believes that there is little if any translocation from remote to budding 

 parts of the tuber even in germinating potatoes, and it seems that its ap- 

 pearance in quantity just before or at germination should be ascribed, in part 

 at least, to metabolic changes induced by other agencies. 



The principal role of manganese in the production of conidia of Asper- 

 gillus niger, G. Bebtrand (Bui. Sci. Pharmacol., 19 (1912), No. 6, pp. 321-324; 

 abs. in Bot. CentU., 122 (1913), No. 3, p. 63).— It is claimed to have been 

 shown that there exists a ratio between manganese on the one hand and iron 

 and zinc on the other in nutritive solutions at which growth of A. niger goes on 

 but no development of reproductive organs takes place. It is said that if in 

 case of a plant in this condition of arrest the proportion of manganese absorbed 

 is increased, the fungus recovers its normal power to develop conidia. 



The influence of boron compounds on plant growth, E. Haselhoff (Landw. 

 Vers. Stat., 79-SO (1913), pp. 399-429, pis. 4).— As the result of investigations 

 carried on for several years with water and soU cultures of com, beans, oats, 

 etc., the author concludes that, while some vei"y low concentrations appear 

 favorable and species show differences, boron exerts on these plants a preju- 

 dicial influence as to appearance and growth. This effect generally begins 

 not far from the concentration of 1 mg. per liter of water in the nutrient 

 medium, in case of boric acid and borax ; but the increasingly injurious effects 

 of these two compounds when added in successively larger proportions diverge 

 to some extent, those of borax increasing generally the more rapidly. The 

 amoimt of boron taken up by different plants showed a general correspondence 

 to the degrees of injury observed. Apparently in case of oats, boron is taken 

 up by the straw and not by the grain. 



The role of oxidases in the formation of the anthocyanin pigments of 

 plants, F. Keeble and E. F. Armstrong (Jour. Genetics, 2 (1912), No. 3, pp. 

 277-311, pi 1, figs. 5). — In continuation of previous studies (E. S. R., 27, p. 632) 

 the authors report on the distribution of oxidases in plant tissues and their role 

 in the formation of pigments. The studies were made principally with Chinese 

 primula (Primula sinensis), sweet william (Dianthus barbatus), and the garden 

 geranium (Geranium sanguineum) . 



