'tempera •ture . 



The temperature data used in this study were all ob- 

 tained from maximum and minimum thermometers read daily at 

 sunset, "^he daily mean temperature was determined by averag- 

 ing- each days maximum and minimum readings. Uhe maximum 

 and minimum temperatures from which the daily means were de- 

 termined were secured from the ^^ublished monthly re-oorts of 

 the U. S. 'Veathei- Bureau. 



vT'assig,,0. L., Climatological Data, Maryland and 

 Delaware Section, numbers from i:ay to November inc. 1914. 

 U. 3. Y^eather Bureau. 



It'cI.ean ha,? discussel some of the possible ways in w'njr>h 

 daily maximum and minimum temperature data may be trea"^ed in 

 order to obtain weighted values that may represent -tempera- 

 ture effect upon plant growth rs.tes. He points out tha" tem- 

 perature values as shown by a thermometer do not -show a linear 

 proportionality to plant growth. If thermometer readings ex- 

 pressed, even in an approximate way, the effect of tempe- 

 rature on growth, s-.ich a rela-''ion could nnly be true up to 

 the optimum temperature, since beyond this point increased 

 terapera*:ure results in decreased growth. It would, therefore, 

 be desirable to replace each thermometer reading by an index 

 representing the efect of that particular temperature on plant 

 growth. Three ways of -lolng -^his, all of which have been con- 

 sidered by McLean may receive brief mention here. 



One way of expressing temperature, which has been \ised 

 in ecological studies, maybe called the remainder sumjTiaticn 



