260 LIVINGSTON— CLIMATIC AREAS [April i8, 



tions of the environment and it is seldom requisite to study the tem- 

 perature of the plant body separately. 



The ability of a plant to withstand unfavorable temperature con- 

 ditions, quite unlike its ability to withstand adverse conditions of the 

 moisture relation, is not at all indicated by structural characteristics. 

 It is absolutely impossible by mere observation or by any morpho- 

 logical study of a plant, to find a basis even for a rational guess as 

 to the temperature conditions to which the organism may be fitted. 

 Furthermore, no method but that of direct experimentation has been 

 devised, and none seems likely to be forthcoming, by which plants 

 may be studied with regard to their temperature requirements, and 

 the appreciation and interpretation- of direct experiment is here so 

 extremely complex that scarcely any attempt has thus far been made 

 in this direction. The result is, that, while we are well aware that 

 temperature conditions are fully as important as those of moisture, 

 in determining plant development and distribution, yet we are with- 

 out any really quantitative knowledge of the heat relation. 



Before such quantitative knowledge can be attained it will be 

 necessary that there be made available somewhere a laboratory so 

 equipped that all of the main conditions of plant growth may be con- 

 trolled and altered at the will of the experimenter. The need of 

 such a laboratory has been emphasized by A. de Candolle and again 

 by Abbe," who also quotes de Candolle, but, so far as I am aware, 

 no serious attempt has ever yet been made to procure facilities for 

 adequate experimental study of the range of conditions which vari- 

 ous plant forms may be able to withstand. The value of such a 

 laboratory to scientific agriculture cannot be overestimated. 



For both the temperature and moisture limits of plant activities, 

 a kind of rough and qualitative experimentation has studied the 

 growth of the same variety of plant in different localities or of dif- 

 ferent varieties in the same locality, and has drawn volumes of vague 

 and more or less discordant conclusions without adequate measure- 

 ment either of the plants employed or of the climatic conditions to 

 which they have been subjected. This sort of experimentation is 



" Abbe C, First report on the relations between climates and crops. 

 U. S. Dept. Agric. Weather Bureau Bulletin 36, 1905. See especially p. 23. 



