214 PHYSIOLOGY [Bot. Absts., Vol. IV, 



million. Hydroxyl concentration in toxic calcium hydrate solution is only about one-third 

 that of toxic sodium hydrate. — When soluble organic matter, acid in reaction and of itself 

 stimulating in concentrations up to 1000, is added to sodium carbonate solution of 400 parts 

 per million, in itself not toxic, a highly toxic solution is formed which kills the root tips. — 

 D. Reddick. 



1420. Btjrd, John S. Rate of absorption of soil constituents at successive stages of plant 

 growth. Jour. Agric. Res. 18:51-72. Fig. 1-13. 1919. — A selected strain of Beldi barley 

 was grown one year in silty clay loam and another year in fine sandy loam, contained in 

 boxes. Precautions were taken that individual plants should have access to equal volumes of 

 soil, that loss of soil constituents in drainage should be avoided, and that plant constituents 

 should not be dissolved and removed by rain. Until the tenth week of growth (phase 1) there 

 was a progressively increasing absorption of nitrogen and potassium, when the absolute 

 amounts of these in the plants were as great as at maturity. From this period until head- 

 ing (phase 2) substantial losses of potassium and nitrogen, and perhaps also of calcium, oc- 

 curred. During seed ripening (phase 3) absorption from the soil ceased and there were losses 

 of all constituents determined in the plants. Dry matter at harvest was found to be propor- 

 tional to the fresh weight at the end of phase 1, at which time the absorption of nitrogen and 

 potassium was proportional to growth. Losses from the plants occurred when the amounts of 

 water soluble soil constituents were at or near their minima. The results are interpreted as 

 showing a movement of chemical elements from the plants to the soil, in response to con- 

 centration differences between the plant sap and the soil solution. It is concluded that a 

 high concentration of the soil extract is probably unnecessary after the first phase of 

 growth. — W. E. Tottingham. 



1421. Crocker, William. Physiological balance in soil and other nutrient solutions. 

 [Rev. of four papers: Hibbard, R. P. Physiological balance in the soil solution. Michigan 

 Agric. Exp. Sta. Tech. Bull. 40. 44 V- 1917. Livingston, B. E., and W. E. Tottingham. 

 A new 3-salt nutrient solution for plant cultures. Amer. Jour. Bot. 5: 337-346. 1918. Shive, 

 J. W., and W. H. Martin. A comparison of the food requirements of the wheat plant at dif- 

 ferent stages of its development. Amer. Jour. Bot. 5: 186-191. 1918. McCall, A. G., and 

 P. E. Richards. Mineral food requirements of the wheat plant at different stages of its de- 

 velopment. Jour. Amer. Soc. Agron. 10: 127-134. 1917.] Bot. Gaz. 67: 175-177. 1919. 



1422. Crocker. William. Knop's solution. [Rev. of: (1) Toole, E. H., and W. E. 

 Tottingham. The influence of certain added solids upon the composition and efficiency of 

 Knop's nutrient solution. Amer. Jour. Bot, 5: 452-161. 1918. (2) Tottingham, W. E. 

 Sulfur requirement of red clover plant. Jour. Biol. Chem. 36:429^38. 1918.] Bot. Gaz. 

 67: 448. 1919. — The reviewer wonders how much more the water culture method alone can 

 add to our knowledge of soil fertility, and suggests that in the concentrated nutrient solu- 

 tions now employed, we may be mainly playing the toxic concentration of one salt against 

 the toxic concentration of another, so as to get the least possible injury. [See Bot. Absts. 2, 

 Entry 1117.]— II. C. Coirtes. 



1423. Green, Newton Baldwtn. The effect of ions of NaCl and CaCl 2 upon the electrical 

 conductivity of certain colloidal mixtures. Plant World 21: 303-316. 7 fig. 1918.— The be- 

 havior of sodium and calcium ions during penetration of several colloids as indicated by 

 measurements of electrical conductivity shows that there is no antagonism between them as 

 regards penetrability; however, calcium moves more slowly than sodium because of its greater 

 adsorption by the colloids. Electrical resistance of colloids containing salts in varying con- 

 centrations, varies directly with the precipitability of the colloid, which is greatest at the 

 isoelectric point. Balanced solutions are believed to owe their effectiveness to the fact that 

 protoplasm, by equal adsorption of + and — ions from them, is brought to the isoelectric 

 point, at which point the proteins are most highly ionized, the greatest amount of precipitate 

 is formed, and the greatest (normal) permeability results. — Charles A. Shull. 



