536 Physiologie. 



träte and Potassium on Absorption and Growth. (Bot. 

 Gaz. L. p. 1-30. fig. 9. July 1910.) 



A study of the growth relationships and concentration differen- 

 ces in Solution cultures of the above salts, varying from a Single 

 constituent to mixtures of two and three in all ratios in 10 per cent 

 stages. The proper correlation and comparisons were made with 

 the aid of the triangulär diagram. 



The better growth occurred when all three nutrients were pre- 

 sent and was best where from 10- 30 per cent phosphate, from 

 30—60 per cent nitrate and from 30 — 60 per cent potash were 

 present. 



The change in the ratio of the Solutions and the ratios of the 

 materials that were removed from the Solutions, showed that where 

 the greatest occurred, the Solutions suffered the least change in 

 ratio, — although the greatest change in concentration took place. 

 The more the ratios, in these Solutions differed from the ratios in 

 which the greatest growth occurred, the more were the Solutions 

 altered, the tendency in all cases seeming to be for the plant to 

 remove from any and all of these Solutions the material in the ratio 

 which normally existed where greatest growth occurred. 



The results show that the higher the amount of any one con- 

 stituent present in the Solution, the more does the culture growing 

 in that Solution take up of this constituent although it does not 

 seem able to use this additional amount economically. In the very 

 early periods the ratio of phosphate absorption is low and the 

 potash absorption high, — although in final growth the greater 

 response is obtained with nitrate, indicating relatively low phos- 

 phate requirement and high potash requirement of the seedling 

 plant. Moore. 



Tpanseau, E. N., A simple vaporimeter. (Bot. Gaz. IL. 

 p. 459—460. fig. 1. June 1910.) 



A small and simple vaporimeter constructed with the aid of a 

 bettle with rubber stopper, a hollow porous tube, partially glazed 

 with cement, and a capülary tube. Moore. 



Wiegand, K. M., The Relation of Hairy and Cutinized 

 Coverings to Transpiration. (Bot. Gaz. IL. p. 430—444. 

 fig. 1. June 1910.) 



Experiments with porous coverings like cotton, wool or hair 

 showed that these must be very thick to produce any appreciable 

 effect in retarding evaporation if the surrounding atmosphere is 

 quiet, but that they become very efficient even in thin layers, when 

 the air is in motion. On the other hand a waxy covering is effective 

 at all times. In sunshine ihe hairy covering shows a greater increase 

 in efficiency than does wax. From these results it seems probable 

 that those plants which have but a moderate water supply, and 

 whose transpiration must be reduced in dry times but not interfered 

 with when the atmosphere is damp, — employ a hairy covering to 

 retard transpiration. Cutin on the other hand is probably employed 

 when there is considerable danger of too great desiccation at all 

 times. Moore. 



