A RELATIVE SCORE METHOD OF RECORDING 



COMPARISONS OF PLANT CONDITION AND 



OTHER UNMEASURED CHARACTERS 



. E. E. FREE 

 The Johns Hopkins University, Baltimore, M<1. 



To all scientific investigators it is a common experience to 

 find need of expressing more or less quantitatively relations 

 which are not strictly commensurable or which for some reason 

 or other are not measured. Students of plants, for instance, 

 find frequent need of comparing the general health or "condition" 

 of different plants and while this comparison is perhaps possible 

 of reduction to precise terms through the actual measurement of 

 turgor, color, speed and intensity of response to stimuli, intensity 

 of metabolic functions, and the like, these units which go to 

 make up the condition are so difficultly and laboriously measur- 

 able that such a procedure is usually impracticable. Ordinarily 

 the judgment of a qualified observer, really formed of course 

 from a more or less unconscious mental consideration of the 

 various single features which go to make up condition, is a more 

 accurate as well as less troublesome index of the existing differ- 

 ences. It has the further advantage of permitting decision 

 immediately or almost immediately while actual measurement 

 of the elements composing the condition would require a time so 

 long as to give opportunity for important change during the 

 progress of the measurement. It results that complex appear- 

 ances such as plant condition are almost never measured in 

 practice but are expressed merely as being better or worse accord- 

 ing to the judgment of the experimenter. 



The fault of this simple comparison is its lack of quantitative 

 expression and this, while unimportant so long as only a few 

 plants are under consideration, becomes very troublesome 

 when many are to be considered or when non-simultaneous 



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