564 EXPERIMENT STATION RECORD. 



The roconls sliow that "the inaxiiuuiii (hiily temperatures occurred hetween 8 and 

 1 1 |i. 111., and the niininunn 12 hours later, or between 8 and 10 a. rn. The oi)tiniuin 

 temperature for al)sorption ])y roots hes well above that of the soil at the depth at 

 which the observations were made. It follows, therefore, that the temperature of 

 the soil approaches this optinmm most nearly, and offers most favorable conditions 

 for the taking up of watery solutions at a time of the day when the amount of water 

 fhrown off by the shoot and of mineral matter used in metabolism are nearing the 

 minimum l)y reason of the absence of light, lowered air temperature, and consequent 

 increased humidity of the air." The influence of these inharmonious conditions in 

 causing guttation excretions from plants is explained. The greatest variation in 

 temperature recorded during 24 hours was 2°C. (3.6° F. ) on June 28 and July 16. 

 The maximum temperature recorded Avas 13.2° C. (56° F.) in July, and the minimum 

 —3° C. (26.6° F.) in December, giving a total annual variation of 16.2° C. (29.4° F.). 

 "Both the maxima and minima are higher in January than in December and are 

 still higher in February, at which time the temperature of the air reaches its annual 

 minimum. As a consequence of the above conditions the roots of plants at a depth 

 of a foot (30 centimeters) in this locality find increasingly more favorable conditions 

 for activity after the latter part of December. . . . The approach of the spring 

 season in this locality therefore finds the root systems and absorbing organs of the 

 vegetation which penetrates the soil to the given depth in a state of comparatively 

 great activity, and it needs but the exposure of a few days or even of a few hours 

 in some plants to allow for very marked development of the stems, leaves, and 

 flowers." 



A notable difference in temperature of the aerial and subterranean portions of 

 plants was observed, and the influence of this condition on the transport of fluids 

 and solutions from one part of the plant to another is explained. 



Investigations on the influence of the volume of the soil on the yield and 

 composition of plants, 0. Lemmermann {Jour. Landw., 51 {1903), No. 3. pp. 

 219-285'). — The residts here reported confirm those of previous experiments (E. S. R., 

 14, p. 1056) in showing a decided relation between the yield and the volume of the 

 soil in which the crop is grown. The experiments here reported were made in 2 

 series of pots, in one of which each pot contained 30 and in the other 15 kg. of soil. 

 All of the pots except those used as checks were supplied with a sufficient amount of 

 the necessary fertilizing constituents. 



The author concludes that the larger yield with the larger pots and the smaller 

 yield from the smaller pots had no relation to the supply of plant food, but depended 

 entirely upon the space which was available for the root development of the individual 

 plants. 



On the lime requirements of soils, and its determination, Immendorff {Oes- 

 terr. Chem. Ztg., 6 {1903), No. 18, p. 412). — This is a brief note on an address before 

 the International Congress of Applied Chemistry at Berlin in 1903. The calcium 

 compounds which are considered of importance in relation to plant nutrition are cal- 

 cium carbonate, calcium combined with humus acids, zeolitic lime compounds, and 

 calcium silicate. As regards their lime requirements, the author classifies soils as 

 follows: (1) Acid soils, prominent among which is sour moor soil, and in which the 

 author recommends that humus acid be determined by means of Tacke's method; 



(2) neutral soils tested by means of boiling with sulphuric acid and titration; and 



(3) alkali soils, which almost always contain calcium carbonate, which may be 

 detected l)y means of hydrochloric acid. In the author's opinion soils should not 

 contain kss than 0.25 per cent of soluble calcium salts. In case of alkali soils the 

 physical properties must also be taken into consideration. 



The importance of calcium and magnesium salts in the nutrition of plants, 

 GossEL {Chem. Ztg., 27 {1903), No. 78, p. 952).— h. brief account is given of experi- 

 ments with water cultures and soils to test the accuracy of Loew's hypothesis regard- 



