488 Physiologie. 



färbten Chloroform die Lösung des roten Salzes sich befindet. Das 

 salzsaure Salz ist ein Holzfarbstoff, die freie Base des Gelbgh^zerin 

 ein Korkfarbstoff. Die Salze des Gelbglyzerin geben also eine' Dop- 

 pelfärbung ftir Holz und Kork. Losch (Hohenheim). 



Skinner, J. J., The antiz5^motic action of a harmful soil 

 constituent: salic37lic aldehyde and mannite. (Plant 

 World. XVm. p. 162—167. 1915.) 



The author presents in this paper the results of studies upon 

 the effect of mannite on growth and upon the circumstances under 

 which this substance exists in soils. Mannite, as such, was found 

 not to be harmful to wheat seedlings in water cultures, but its 

 decomposition products in nutrient Solutions containing phosphates 

 were decidedly harmful. Salicylic aldehyde was found to prevent 

 the bacterial decomposition of mannite, but was harmful to the 

 growth of plants as well as to bacterial life. The existence of mannite 

 in garden soil is believed to be made possible b}?^ the simultaneous 

 presence of salicylic aldehj^de. Sam F. Trelease. 



Tottingham, W. E., A quantitative chemical and ph5^sio- 

 logical study of nutrient Solutions for plant cultures. 

 (Physiological Researches L p. 133—245. f. 1 — 15. 1913.) 



A detailed experimental investigation showing the influence,^ 

 upon the growth of young wheat plants, of a wide ränge of propor- 

 tions of the component salts in nutrient Solutions and alterations in 

 this influence by different total concentrations. A preliminary che- 

 mical study involving the preparation of stock Solutions, concentration 

 limits of Stahle Solutions, and the nature of the changes causing 

 precipitation, was made of Knop's nutrient Solution for plants. It 

 was found convenient to employ two parts in preparing concentrated 

 stock Solutions according to Knop's formula, one part («) containing 

 only calcium nitrate, and the other part {b) containing the rcmaining 

 three salts. From the point of view of stability it was found prefe- 

 rable to use KH2PO4, rather than K0HPO4 in the preparation of 

 this Solution. Analytical investigation of the changes occuring in 

 Knop's Solution above the concentration limit of stability showed 

 that precipitation was due to the formation of CaSO^. In the main 

 part of the study, three different total concentrations (0.05, 2.50, and 

 8.15 atmospheres of possible osmotic pressure) of the salts of Knop's 

 Solution were emplo3^ed. In each of these cases the approximate 

 osmotic pressure was divided into ten equal parts, and these ten 

 parts were distributed among the four component salts of Knop's 

 Solution in all possible ways, thus giving eighty-four Solutions for 

 each series. The evaporating power of the air in the greenhouse 

 used was measured by means of a Livingston Standard cylindri- 

 cal porous cup atmometer, and comparative rates of transpiration of 

 selected cultures from each series were determined for a short 

 period preceding harvest. Yields of roots and tops, as well as various 

 other quantitative data on growth, are presented, partly by the aid 

 of triangulär diagrams, The ratio of magnesium to calcium was 

 found to be the most important factor in determining the effects ot 

 ihe different proportions of the various salts in the nutrient Solutions. 

 The author's best nutrient Solutions produced much better growth 



