126 EXPEEIME]SrT STATION RECORD. 



The influence of contact with the soil on the absorbability of soluble 

 phosphates, C. Schreibeb (Rev. Gen. Agron., n. ser., 2 (1907), No. 2, pp. 

 .i.9-JJ). — Pot experiuients with superphosphate, Thomas slag, and precipitated 

 phosphate on ferruginous soil are reported which show that prolonged contact 

 with the soil destroys the absorbabilitj'^ of available phosphates. This retro- 

 gression varies with the character of the phosphate, being much greater in the 

 case of superphosi»hates than of Thomas slag and precipitated phosphate. 



Wolters phosphate, E. Wein (Dent. Laiidic. Pres.se, 3't (1907), No. 35, pp. 

 289, 290). — Comparative plat tests of Wolters sodium phosphate and potassium 

 phosphate, supei'phosphate, and Thomas slag on nuistard, meadows, potatoes, 

 barley, oats, and clover, show the Wolters phosphate to be readily availal)le and 

 as effective as superphosphate. 



Ground limestone for acid soils, C. G. Hopkins (Illinois Sta. Circ. 110, pp. 

 19, flf/s. 3). — The character and action of caustic and carbonate lime are briefly 

 explained. The advantages of limestone over caustic lime for use under 

 ordinary conditions in Illinois are pointed out, and the best methods of apply- 

 ing lime on such soils are outlined. 



"As a general rule, we should use lime only to correct the acidity of the soil, 

 and this is necessary only where tliere is difficulty in obtaining a good stand 

 ?.nd luxuriant growth of a leguminous crop, such as red clover. As to the 

 form of lime to use for this purpose, the farmer must be governed somewhat 

 by the cost of the material. Fine-ground limestone will be both the best and 

 the most economical form of lime to use wherever it can easily be obtained. If 

 caustic lime be used, we should mal<e special provision to maintain the humus 

 in the soil." 



The conclusions drawn are based upon experiments by the Pennsylvania and 

 Maryland stations, as well as on those carried on for a number of years l)y the 

 Illinois Station. As an average of 50 tests carried on by the latter station 

 " during the last 3 years on the soil experiment fields at Vienna in Johnson . 

 County, at Cutler in Perry County, at Dubois in Washington County, at Odin in 

 ■ Marion County, and at Edgewood in Effingham County, the value of the in- 

 crease pi'oduced by lime or ground limestone has been $2.69 ah acre a year, 

 counting corn worth 35 cts. a bushel, oats 25 cts., wheat 70 cts., and clover h;iy 

 worth $G a ton. As an average of 20 tests on these fields, the yield of corn has 

 been increased 0.6 bu., and as an average of IS tests the yield of wheat has 

 been increased 4.8 h\\. per acre, both of tliese crops being grown in rotation 

 with legume crops on both the limed and unlimed land. As an average of 7 

 tests the yield of clover has l^een increased 0.37 ton of air-dry hay per acre, 

 and liming has increased the yield of oats 10 bu. per acre, but this is an average 

 of only 5 tests." 



AGRICULTURAL BOTANY. 



Some factors determining the structure of plants, J. Laurent (Rev. Gen. 

 Bot., 19 (1907), No. 220. pp. 129-160). —A study was made of a number of the 

 factors that determine the structure of plants, and as a result of his investiga- 

 tions the author concludes that of the internal factors changes in turgescence 

 through changed osmotic pressure produce the principal variations in growth, 

 and that of a considerable number of specific factors studied those capable of 

 increasing osmotic pressure are capable of influencing the structure of the plant. 

 A biltliography is appended. 



Notes on polyenibryony, M. T. Cook (Torreya, 7 (1907), Xo. 6, pp. 113- 

 117, figs. 3). — On account of the importance of plant-l)reeding experiments witli 

 tropical fruits, the author describes cases of polyembryony in the mango and the 



