1919] AGRICULTURAL BOTANY. 827 



larly in Porto Rico. Legislation pertaining to commercial fertilizers in Porto 

 Rico is reviewed and various commercial fertilizer materials described. 



The results of the actual and guarantied analysis of commercial fertilizers 

 and fertilizing materials examined during the period from July 1, 1917, to 

 August 31, 1918, are presented in tabular form. 



The international movement in fertilizers and chemical products useful 

 to agriculture. 1918 {Intcrnat. Inst. Agr. [Rome], Bur. Statis. Doc. Leaflet, 

 3 {1919), No. 5, pp. //4). — Tables are given which include fairly complete data 

 on production, trade, and prices for the years 1913 to 1918, inclusive. 



AGRICULTURAL BOTANY. 



[Plant studies], J. A. Harris {Carnegie Inst. Washington Year Book, 17 

 {1918), pp. 116, 117). — This is a brief report of investigations along various 

 lines, including osmotic concentration of vegetable saps, variation and correla- 

 tion in plants, and variation, correlation, and selective death rate in garden 

 beans. 



[Plant ecology], F. E. Clements {Carnegie Inst. Washington Tear Book, 17 

 {1918), pp. 287, 288). — The principles of synthetic ecology have served as a 

 guide in tlie experimental work centered at the Alpine Laboratory on Pike's 

 Peak and around Colorado Springs and Tucson. It has been recognized that 

 animals contribute a factor of profound importance in all plant associations, 

 and steps have been taken to begin a quantitative study of this influence. 

 During the year emphasis has been laid upon plant indicators, climatic cycles, 

 and grazing research. A notable feature is the employment of standard plants 

 as indicators in the study of transpiration and rate of growth. 



The phytometer method, F. E. Clements, J. E. Weamle, and F. C. Jean 

 {Carnegie Inst. Washington Year Book, 17 {1918), pp. 288, 289). — Batteries of 

 standard plants, termed phytometers, have been installed and three series 

 have been measured. The plants employed have been wheat, oats, sunflower, 

 Jind raspberry {Riihus strigosus), all of these growing readily at different 

 altitudes. The method promises to be of great value in interpreting climates 

 and soils in terms of plant behavior and perhaps to exceed in value analysis 

 hy physical instruments. It should, it is thought, have wide application in 

 dry land agi'iculture, grazing, and forestry in determining the possibilities 

 of climates and soils and in definitizing the use of plant indicators. 



Permanent quadrats, F. E. and E. Clements and G. V. Loftfield {Carnegie 

 Inst. WasJiington Year Book, 17 {1918), pp. 295, 296). — Progress is reported in 

 the work of extending the number of quadrats for the exact quantitative study 

 of climax formations and their succession. In the attempt to secure a record 

 of the plant parts below ground a quadrat-bisect method has been devised by 

 which depth, spread, and competition relations may be charted for wet and 

 dry phases of the cycle. 



Ecology of root systems, J. E. "Weaver {Carnegie Inst. Washington Year 

 Book, 17 {1918), pp. 291, 292). — Examination of the root systems of a large 

 number of dominant and subdominant species of important plant communities, 

 with reference to their relation to the nature of the soil, the amount and 

 penetration of the water content, and competition with each other, is said to 

 have shown that the character and location of the root system were correlated 

 with the water content in nearly all cases. Plains and prairies are much 

 alike in regard to root behavior, except that roots of plains species tend 

 to spread laterally while those of the prairie species go more directly down- 

 ward. The gi-eat majority of the roots are highly plastic, those of ecads 

 especially so, but some species, as Kceleria cristata and Allionia linearis, pos- 



