9H 



plants and that growth rates are therefore, -from this point of 

 view, themselves a measure of the ability of the environment 

 to r)roduce growth. It is assumed that such a method of measur- 

 ing the environment is susceptible of "standardization". That 

 is, certain plants may be selected for use as integrating in- 

 struments, their growth pe^uliarites studied, and conditions 

 defined under which their gro'A'th rates would measure this or 

 that environmental condition or complex of conditions. It 

 is suggested that the measurement of environment in terms of 

 the growth of standard plants, assuming that it is possible 

 to standardize them, would in all orobability give results 

 applicable directly to many purely scientific and practical 

 problems. In the present exr)eriment an attempt is made to 

 grow soy beans \mder experimental conditions so controlled 

 that the growth of the plants constitutes a measure of a cer- 

 tain part of the environmental complex ordinarily termed cli- 

 matic, the environmental factors here measured being tempe- 

 rature, sunshine and evaporation. 



From this point of view, every gwowth rate for each of 

 the cultures, both two- and four-week is a measure of the 

 climatic complex made up of the temperature, sunshine and evap- 

 oration conditions acting on the pl=ints during the period for 

 which the cultures under consideration was growing. It is, 

 of course, realized tha "^ in the present experiment the con- 

 trol of the environmental factors other than the ones to be 

 measured in terms of the growth of the plants was far :^rom 

 complete, and tha"- the above statement Is thus only approxi- 

 mately true. Assuming, however, that the control of conditions 

 other than the one to be measured was such that the growth 



