288 CARNEGIE INSTITUTION OF WASHINGTON. 



pine zones. Areas have been fenced against rodents especially, and 

 instruments installed in the short-grass plains at 6,000 feet, and in 

 chaparral and in the pine consociation at 7,000 feet. In the moun- 

 tains, similar installations have been made in the gravel and half- 

 gravel associes and in the Douglas-fir climax at 9,000 feet. Each 

 station was equipped with recording instruments for temperature, and 

 humidity, and with rain-gages and porous-cup atmometers. Weekly 

 readings were made of the water-content and several series of light 

 readings were obtained. The most striking feature was the use of 

 standard plants to determine the transpiration and rate of growth, 

 as explained in the following paragraph. The quantitative results 

 thus obtained have been used in practically all of the experimental 

 studies indicated below, and some of the details are given in the pub- 

 lished accounts of these. While the instrumental data have much 

 value in dehmiting the climates and habitats, it seems best not to 

 publish them until they have been obtained for another year or two, 

 when it will be possible to make effective comparison with similar 

 results secured from 1902-1906. 



The Phytometer Method, by F. E. Clements, J. E. Weaver, and F. C. Jean. 



The pubUcation of Research Methods in Ecology in 1905 was due 

 to the conviction that ecology to progress must become a quantita- 

 tive science. In the endeavor to accompUsh this, practically all the 

 accepted meteorological instruments were employed and a number 

 of new instruments were devised for habitat analysis. During the 

 twenty years that have elapsed since the first quantitative analyses 

 of habitats in 1898, the value of instrumental methods has become 

 generally recognized. As the attention of the ecologist became cen- 

 tered more upon the plant, however, it was found that instrumental 

 data often threw little or no light upon the plant's behavior because 

 of the difficulty of changing from a physical to a biological system. 

 In the hope of remedying this, an endeavor has been made to devise 

 a biological method of measuring habitats by means of standard 

 plants. Batteries of such plants, for which the term "phytometer" is 

 suggested, have been installed at the various factor stations, and three 

 series have been measured during the summer. The plants employed 

 were wheat, oats, sunflower, and raspberry (Ruhus strigosus), all of 

 which grew readily at the different altitudes. They were grown in 

 the same kind of soil in sealed containers and were protected from 

 rodent damage by fences of wire netting. A record was kept of the 

 water-loss from week to week, as well as of the various physical fac- 

 tors, and the results have been expressed in terms of water-loss in 

 relation to unit leaf-surface and to dry weight, of photosynthate pro- 

 duced per leaf -unit, and in terms of growth. The method promises 

 to be of great value in interpreting climates and soils in terms of plant 



