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METHODS IN THE QUANTITATIVE ANALYSIS OF 

 PLANT GROWTH— A REPLY TO CRITICISM. 



By G. E. BRIGGS, F. KIDD and C. WEST. 



The Chief Statistician at the Rothamsted Experiment Station in his 

 criticism of the methods put forward by us in recent articles (4 & 5) on 

 The Quantitative Analysis of Plant Growth, summarises his remarks 

 as follows. "The methods of calculation formulated by Briggs, Kidd 

 and West for the analysis of plant growth are inaccurate." We feel that 

 this sweeping statement standing in the forefront of the conclusions of 

 what might appear to be an authoritative utterance by a statistician 

 cannot be allowed to pass unanswered, the more so in that it is not 

 supported by evidence or argument in the body of Mr Fisher's paper. 



The Method. 



The general method proposed by us for a quantitative analysis of 

 plant growth is to obtain from primary data recorded at frequent 

 intervals throughout the life of the plant, secondary relations 1 . We 

 proposed the following as being probably the most useful at the outset. 



1. Relative Growth Rate. 



2. Leaf- Area Ratio. 



3. Unit Leaf Rate. 



4. Relative Leaf Growth Rate. 



We suggested that by a careful comparison of these with each other 

 and with records of environmental factors one might be able to dis- 

 entangle problems of plant growth and thus eventually to evaluate plant 

 constants. We do not wish it to be concluded that we proposed these as 

 the only significant secondary relations. For example, from an analysis 

 of the results of growth experiments carried out by us more recently 

 it appears that the ratio of the rate of growth to the rate of respira- 

 tion is a further significant secondary relation. 



The question of the value of this general method is not dealt with 

 by Mr Fisher, and indeed can only be decided by the results obtained 

 from its application. 



1 For details of these secondary relations the reader is referred to (5). 



