256 J. ARTHUR HARRIS AND H. S. REED. 



ment is clearly significant in comparison with its probable error. 

 The coefficients are lower for the 35th and the 42d day, but are 

 probably statistically trustworthy. Beyond this period there 

 seems to be no relationship between the size of the organism and 

 its growth rate in an immediately following period. 



For the first two stages of growth measured, the 7th and the 

 I4th day, there may be a significant correlation of the order 

 r = -)- .285 between size and growth increments during the sec 

 ond following week. 



The coefficient of correlation between size and the increment 

 in the second week following is also positive for the 2ist and 

 28th day, but neither of these values may be considered statis 

 tically significant in comparison with its probable error. Finally 

 for the first stage (seventh day) there may be a significant cor 

 relation between absolute size and growth increments during the 

 third week following (r=-f-.239 for increment for 2ist to 28th 

 day). Other than this the coefficients are for the most part sta 

 tistically insignificant in comparison with their probable error. 



Summarizing the preceding statements as a basis for further 

 analysis, we note that for the first six growth stages (7th to 42d 

 day) there is a significant positive correlation between the size of 

 the organism at the given stage and the growth increment of the 

 following week. For the first two growth stages (and possibly 

 in the third where r/E r =i.jj} there is a significant correlation 

 between the size of the organism and the growth increment in 

 the second subsequent week. Finally, for the first stage only, 

 there is a significant positive correlation between size and growth 

 increment in the third subsequent week. 



Disregarding these 9 coefficients and the 4 positive but not sig 

 nificant correlations between the sizes at the several growth stages 

 and the growth increments of the following week, we may note 

 the following facts concerning the remaining 42 coefficients. 



Of these 42 coefficients 36 are negative while only 6 are posi 

 tive in sign. Of the 6 positive coefficients only that between 

 actual size on the 2ist day and growth increment between the 

 28th and 35th day (already considered above) is as large as its 

 probable error. Of the 36 negative coefficients 18 are larger than 



