184 Physiologie. 



the plant cannoi recover turgidit)'- without additional moisture being 

 supplied. The method employed to overcome these difficulties con- 

 sisted in growing plants in small glass pots, evaporation from the 

 soil surface being prevented by a seal of wax consisting of a mix- 

 ture of parafin and vaseline. During growth the pots were immersed 

 in a water bath. The probable error does not usually exceed 

 0.1 per cent. of actual soil moisture. Moore. 



Dandeno, J. B., Mutual Interaction of plant roots. (Mich. 

 Acad. Sei. llth Rep. p. 24—25. fig. 1—2. June, 1909.) 



Pot experiments showing the "stimulating" effect of Canada 

 thistle on oats, barley and wheat. With buckwheat the results were 

 reversed. Oats aecompanied by young elm trees gave less growth 

 than oats alone. Also some field observations. Moore. 



Eikenberry, W. L., An atmograph. (Bot. Gaz. L. p. 214—219. 

 fig. 1—4. Sept. 1910.) 



Description of an appratus designed to work with the porous 

 cup atmometer, which will automatically measure and record evapo- 

 ration at all tiraes. The device consists essentially of an oscillating 

 beam, which may be caused to tilt by the movement of mercury 

 in a tube and its connecting bulbs, advantage being taken of the 

 oscillation to open and close certain stop cocks. At the same time 

 an electric cireuit is closed which actuates the pen of the Chro- 

 nograph. Moore. 



Goodspeed, T. H., The temperature coefficient of the 

 duration of life of barley grains. (Bot. Gaz. L. p. 220—224. 

 March 1911.) 



Carefully selected barley, from which the inferior palea had 

 been removed, were soaked in tap water for one hour and subjeeted 

 in water to constant temperatures for definite periods. The duration 

 of life of the seeds was taken to be the time in minutes for which 

 a given temperature must act in order to inhibit the subsequent 

 growth of all the seeds when placed under favorable conditions. 

 The criterion for complete development was the appearance of the 

 green shoot above the plumule sheath or the formation of roots 

 from the swollen radical end. 



The temperature coefficient of the duration of life of barley 

 grains was determined for 55°— 70° C. and found to be about 11 for 

 temperature interval of 10°. Moore. 



Livingston, B. E., Operation of the porous cup atmometer. 

 (Plant World XIII. p. 111 — 119. May, 1910.) 



Discussion of some of the difficulties which have been met in 

 operating this instrument and means of obviating them. Correction 

 of readings, standardization, reduetion of corrected readings to 

 depth, micro-organisms in cups, duplication of instruments, renewal 

 of clogged cups, preparation of distilled water for use in atmometer 

 and correction for absorption b}^ rain, — are all treated. Moore. 



