INTER-PERIODIC CORRELATION. 



249 



The same type of diagram may be used to show the relation- 

 ship between the size at early and at later growth stages. Dia- 

 gram 2 shows the distribution of the magnitudes of the correla- 

 tions for sizes of the individuals at the 7th to the 7oth day (stage) 

 and the size at subsequent growth stages. 



From these lines it is clear that the correlations between size 



1-0 

 9 

 8 



r 



14 21 28 35 42. 49 56 

 /JG OF PLAA/T (STAGE) 



DIAGRAM 2. 



63 



70 



77 



at antecedent and subsequent periods decrease as the periods be- 

 come more widely separated in time. This is true without ex- 

 ception for every period which furnishes evidence upon the 

 question. 



The coefficients are, however, positive in sign throughout, thus 

 suggesting (though in some cases not proving) that throughout 

 its growth period the size of the plant bears some relation to its 

 size when first measured. This result is in agreement with the 



