AGEICULTtJRAL BOTANY. 327 



Wool and leather wastes, E. J. Russell {Jour. Bd. Agr. [London], 21 

 (1915), No. 12, pp. 1087-1092).— The fertilizing value of shoddy as indicated 

 by analysis and by the results of field ex])erinients is briefly discussed. A 

 note is also given on the fertilizing value of leather waste, emphasizing particu- 

 larly the necessity of treating the leather with sulphuric acid to make it more 

 available as a fertilizer. 



A note on the export of manures from India (India Tea Assoc, Sci. Dept. 

 Quart. Jour., No. 2 (19U), pp. 49-51).— Data for the years 1910-11, 1911-12, 

 and 1912-13 for exports of bones, fish manure and guano, oil cake, and other 

 fertilizing materials are tabulated. 



A pronounced increase in exports of all kinds of fertilizing materials occurred 

 during the period named. The increase was especially markqd in the case of 

 oil cake. The figures for 1912-13 are as follows : Bones, 110,221 long tons, 

 valued at $2,558,245.97; fish manure and guano, 21,408 tons, valued at $337,- 

 768.52; oil cake, 3,235,703 tons, valued at $3,996,869.14; and other fertilizing 

 materials, 8,338 tons, valued at $247,630.74. The largest importers of bones 

 were, in the order named, Belgium, France, the United Kingdom, Germany, 

 Japan, and Ceylon ; the United States imported 7,761 tons. Tbe larger propor- 

 tion (17,885 tons) of the fish manure went to Ceylon. Of the oil cake the 

 largest importers were, in the order named, Ceylon, United Kingdom, Japan, 

 and Germany. The use of fertilizers in Ceylon, esi)ecially in tea culture, is 

 comparatively large and steadily increasing. 



AGRICTJLTTJIIAL BOTANY. 



Inorganic plant poisons and stimulants, Winifred E. Brenchley (Cam- 

 bridge: University Press, 1914, PP- X+110, pis. 7, figs. 12). — The author gives 

 an account of investigations on the toxic effect of compounds of copper, zinc, 

 arsenic, boron, and manganese on different species of plants. 



Summarizing the results obtained, she states that copper compounds act as 

 poisons to higher plants, and that only under particular and peculiar conditions 

 and in very great dilutions is any stimulative action clearly demonstrated. 



Zinc compounds are somewhat less toxic to higher plants, and their stimu- 

 lating influence is still considered uncertain except in very great dilutions. In 

 soil cultures increased growth seems to have been established, as certain 

 species of plants respond to zinc salts, though no increase is obtained with 

 other species. Among the fungi, particularly with Aspergillus niger, the stimu- 

 lating effect is recognized. 



The toxic effect of arsenic upon higher plants was found much more marked 

 with arsenious acid and its compounds than with arsenic acid and its deriva- 

 tives. With certain alga? stimulation may follow the presence of arsenic com- 

 pounds under certain conditions, while with fungi it appears that some species 

 are able to live in the presence of arsenical compounds. 



Among the boron compounds boric acid is said to be less harmful than are 

 the compounds of copper, zinc, and arsenic. There seems to be evidence that 

 below a certain limit of concentration boron exercises a favorable influence 

 upon plant growth, encouraging the formation of stronger roots and shoots. 

 Fungi appear to be very indifferent to boron, and there is said to be evidence to 

 show that certain green algae can Mnthstand large quantities of it. 



Manganese exerts a toxic influence on the higher plants if present in high 

 concentration, but in the absence of an excess of manganese compounds the 

 poisoning effect is overshadowed by a definite stimulation. It is considered 

 probable that manganese may prove to be an element essential to the economy 

 of plant life, even though the quantity usually found in plants is very small. 



