ECOLOGY. 289 



behavior and bids fair to relegate analysis by physical instruments 

 to a secondary place. It should find wide application in dry-land 

 agriculture grazing, and forestry, in determining the possibilities of 

 climates and soils, and in definitizing the use of plant indicators. A 

 detailed account of the method and of the results is being prepared 

 for publication. 



Photosynthetic Efficiency, hy F. E. Clements and Frances Long. 



The recent chemical methods of estimating carbohydrates in plants 

 have been somewhat refined and appHed to the problem of measuring 

 the food-making activity of plants under natural conditions. Two 

 major lines of study have been followed, one deaUng with the 

 same plants under different conditions, and the other with different 

 species under the same conditions. The former has received the 

 chief attention in the field, and it is expected to give more attention 

 to the latter under control conditions during the fall. The standard 

 plants used as phytometers have served to show the photosynthetic 

 behavior of different species in several habitats as well as the effi- 

 ciency of each species in different habitats. In addition, studies have 

 been made of the photosynthetic activity of ecads growing naturally 

 in sun and in shade and of paired species found in opposite fight 

 conditions. An attempt has also been made to determine the rate of 

 carbohydrate production during the day, and its relation to the curve 

 of daily light intensity. Factor readings have been secured in all 

 cases and especial attention has been paid to light intensity and qual- 

 ity. The method is expected to prove of especial value in forestry, 

 where reproduction and growth are largely determined by the light 

 intensity. It should also prove useful in permitting comparisons of 

 the food-making efl5ciency of varieties of crop-plants, as well as of 

 native species. 



Behavior of Stomata, hy G. V. Loftfield. 



This work is in continuation of investigations carried on at the 

 Experiment Station of the American Smelter and Refining Company 

 at Salt Lake City, under Dr. P. J. O'Gara, in 1916. Forty species of 

 crop plants were studied to determine the relation of stomata to the 

 injurious action of smelter fumes upon plant tissues. To accompfish 

 this, it proved necessary to ascertain the behavior of the stomata of 

 both leaf surfaces throughout the day and night. This was done by 

 removing strips of epiderm from the leaf at hourly intervals throughout 

 a 24-hour period and fixing the stomata in absolute alcohol. The 

 strips were mounted and micro-photographed to jdeld a series of 48 

 prints, showing the openings of the stomata on both surfaces for every 

 hour of the day and night. At the same time, complete records were 

 taken of the physical factors by means of recording instruments. 



