626 EXPEEIMENT STATION RECORD. 



In these plants stable manure is allowed to ferment in a concrete-lined 

 pit at a temperature of about 100° F. for from 20 to 30 days. It is then 

 forked over, spread out in layers 1 ft. thick, to which 5 per cent by volume 

 of wood ashes aud 2 per cent of slaked lime are added, and the mixture covered 

 with a layer of loam soil ranging from 50 to 150 per cent of the total volume, 

 depending upon whether the manure was pure or mixed with much straw. 

 The heap is built up of alternate layers of this kind to a height of about 

 8 ft. and allowed to stand about 60 days to disintegrate. 



It is stated that at the end of this time about SO per cent of the material will 

 pass through a i-in. mesh. Material coarser than this is returned to the 

 manure heap for further disintegration. 



It is stated that from 8,000 to 10,000 cu. yds. of such fertilizer is now being 

 manufactured per annum, at a factory cost of $1.38 per cubic yard, any surplus 

 over the needs of the department finding a ready sale at $2 per cubic yard 

 at the factory. 



The international movement of fertilizers (Intemat. Inst. Agr. [Rome'], Mo. 

 Bui. Agr. Intel, and riant Diseases, 6 {1915), No. 3, pp. 323-370).— This review 

 issued in March, 1915. " contains, as far as possible, final figures for the ferti- 

 lizer production and trade in 1912 and 1913, together with provisional figures 

 for 1914, according to the scheme outlined in the first number of the review 

 which was published in September, 1914" (E. S. R., 32, p. 425). Two new 

 tables have been added to those appearing reg-ularly, one referring to the world's 

 production of natural guano and the other to the production of superphosphate 

 in the different countries. An estimate of the natural reserves of phosphates 

 in the United States is also included. The report contains no figures relating 

 to the production of potash salts in Germany. 



A bibliography of 178 references to recent literature on the subject of ferti- 

 lizers is appended to the detailed tables of production, imports and exports, 

 consumption, and prices. 



Importation of fertilizer materials, B. Y. Ordonez (Rev. Asoc. Rural 

 Uruguay, 44 {1915), No. 3, pp. 173-186). — This article reviews the laws of 

 Uruguay relating to trade in fertilizers and describes the official methods 

 employed in inspection. 



AGRICTJLTTTRAL BOTANY. 



The measurement of electrical conductivity as a method of investigation 

 in plant physiology, W. Stiles and I. Jorgensen {New Phytol., 13 {1914)," 

 No. 6-7, pp. 226-242, figs. 5). — Giving a partial review of the work already done 

 by others toward making use of electrical conductivity measurements in 

 questions of plant physiologj', the authors report on the methods and results 

 of their own studies in this direction. They hold it probable that (while use 

 of these methods is still in its preliminary experimental stage) with further 

 development of methods, electrical conductivity may afford a convenient and 

 comparatively simple means of investigating certain classes of problems in p^ant 

 physiology. 



A bibliography is appended. 



A new theory regarding the feeding power of plants, E. Truog (Science, n. 

 ser., 41 (1015), No. 1060, pp. 616-618).— As a result of investigations on the 

 feeding power of plants the author proposes the following hypothesis : 



" Plants containing a relative high calcium oxid content have a relatively 

 high feeding power for the phosphorus in raw rock phosphate. For plants 

 containing a relatively low calcium oxid content the converse of the above is 



