662 Physiologie. 



stration of fatigue or exhaustion after successive stimulations. The 

 lips were mechanically stimulated to bring about closure, and the 

 time-period required for them to return to their original position 

 determined. The first few Stimuli result in increased rapidity of 

 opening; then opening becomes gradually slower after each succes- 

 sive closure, and finally there is a rather sudden loss of the power 

 of movement. Sam F. Trelease. 



Burns, G. P., The relative transpiration of white pine 

 seedlings. (Plant World. XVIII. p. 1—6. 1915.) 



Studies involving measurements of evaporation from white and 

 from black cylindrical porous cup atmometers placed among seed- 

 lings of white pine in three degrees of light, and also determination 

 of transpiration and of chemical composition of these seedlings. The 

 'approximate amounts of water transpired per seedling, in "noshade", 

 in "half shade", and in "fullshade" respectively, were found to be 

 in the proportions of 21, 8, and 1, while the corresponding dry 

 weights produced were approximately proportional to 6, 3, 5, and 1. 

 The corresponding ash contents, in per cent. of dry weight, were 

 8.29%, 9.350/0, and 10.20%, making the total amounts of ash ob- 

 tained proportional to 5, 3, and l, respectively. Thus with a water 

 absorption of 20 the ash content is only five times as great as with 

 an absorption of unity, etc. Nitrogen content, in per cent., of dry 

 weight, was 2.18%- 2,70 o/q, and 6.89% under the three conditions, 

 respectively. The author draws the conclusion that "the explanation 

 of the differences in size and chemical composition of the three 

 groups of trees must be sought along the line of photosynthesis and 

 assimilation, rather than along the line of absorption and transpira- 

 tion". Sam F. Trelease. 



Hill, G. R., The relation of Ventilation to the keeping 

 qualities offruits and vegetables. ( Washington Universitj^ 

 Studies I. p. 46-64. 1913.) 



Experimental studies upon the keeping qualities of fruits and 

 vegetables in relation to insufficient oxygen and to an accumulation 

 of carbon dioxide, attempting to explain the injur}^ occuring to fruit 

 in refrigerator cars as due to lack of proper aeration. It was found 

 that apples, peaches, and lettuce kept well in air, but spoiled quickly 

 in nitrogen, hydrogen, and carbon dioxide, the injury not being 

 due to microörganisms. A study was also made of the production 

 of carbon dioxide by fruits in air, in nitrogen, and in hydrogen. 

 Cherries, blackberries, and grapes produced as much carbon dioxide 

 in nitrogen and in hydrogen as in air, while green peaches produced 

 only about half as much carbon dioxide in the absence of oxygen 

 as in its presence. Carbon dioxide was produced less rapidh^ by 

 grapes than by cherries, and the latter spoiled more quickly than 

 the former. It is suggested that, since enzymes are supposed to 

 produce the injury, the rate of "spoiling" in fruits is more or less 

 directly proportional to the content of carbon dioxide producing 

 enzymes. Sam F. Trelease. 



Lehenbauer, P. A., Growth of maize seedlings in relation 

 to temperature. (Physiol. Res. I. p. 247—288. f. 1—5. 1914.) 

 The fact that different inyestigators of the relation of tempe- 



