2 GEORGE P. BURNS 



sometimes lengthy description of the meteorological conditions 

 of the region under consideration. These are usually taken from 

 the nearest station of the United States Weather Bureau, and 

 include sunshine records, air temperature records, wind records, 

 etc. The next section in these papers gives a detailed account 

 of the plant societies of that region, their distribution, history of 

 their development, facts concerning the water, etc., of the habitat, 

 but one looks in vain for any important use of the data obtained 

 from the Weather Bureau. The writer feels that there is a mean- 

 ing, and feels it so strongly, that he includes the data in his con- 

 tribution, but he is at a loss to know what they mean in terms of 

 the plant. 



A third group of ecologists, realizing that they can not use 

 to good advantage the data from the Weather Bureau, has 

 attempted to gather their own data, limiting themselves for the 

 most part to a study of evaporation. Many valuable data are 

 being collected by this group of workers. The method consists, 

 roughly, in determining the amount of water evaporated from 

 porous cups in different habitats. These cups are' usually placed 

 near the surface of the ground even when determining the evap- 

 oration in forest societies. 



A fourth group of ecologists is studying the effects of me- 

 teorological conditions on plant activities. Recording instru- 

 ments for percentage of sunshine, percentage of humidity, air 

 temper, ^ure, soil temperature, etc., are placed not at some high 

 elevation above the plant society under consideration, but under 

 the same conditions as those in which the plants are working. 



For example, Livingston has attempted to determine the rela- 

 tion of the evaporation from the porous cup to the transpiration 

 from a given plant. He believes that the porous cup is the best 

 means yet devised for measuring the factors which influence 

 evaporation. But such data of themselves are not valuable 

 until the relation of the evaporation from the porous cup to the 

 transpiration from the living plant can be determined. He, 

 therefore, works out the sun-shade ratio for white, black and 

 brown atmometers, and several plants. This, to my mind, is 

 one of the most promising fields of research in ecological botany. 



