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THE POPULAR SCIENCE MONTHLY 



base line twenty-five degrees below the upper limit of the temperature 

 to be estimated, by arcs of the curves marking the hours, and by the 

 crooked line traced by the pen as a result of changes in temperature, as 

 shown on the accompanying sheet (Fig. 7). 



The areas of such figures for temperatures is multiplied by the 

 factor 4.5 for temperatures between 40° and 65° F., and by 20 for 

 temperatures between 65° and 70° F., and by 45 for temperatures 



JAN. 



FEB. 



MARCH 



APR. 



MAY 



JUNE 



Fig. 8. Growth-values During the First Six Months of Two Years at 

 the Coastal Laboratory, Carmel, Calif. The solid line shows temperature effects 

 in 1912, the broken line during 1913. 



between 70° and 75° F., by 70 for temperatures between 75° and 

 80° F., by 78 for temperatures between 80° and 86° F., the opti- 

 mum, etc. Time does not suffice to mention the necessary corrections, 

 or the studies being made for the refinement of the method, but atten- 

 tion may be called to the estimation of the temperature factor by this 

 method at our two main experimental localities during the first four and 

 six months of two years at the Desert Laboratory, and the Coastal Lab- 

 oratory (Fig. 8). The facts displayed in the accompanying figure go 

 far to explain the divergent action of species under observation in the 

 two places. Studies are now in progress for the redetermination of the 

 factors expressing the rate of growth under the ordinary swing of daily 

 temperatures and for an exacter application of the results. 



There is much reason to believe that in the integration of the tem- 

 peratures and moisture relations by the methods outlined we will be 

 able to identify the causation of the remarkable evolutionary departures 



