206 Quantitative Analysis of Plant Growth 



values for increase in dry-weight per unit leaf-area vary more or less 

 about a mean and that the fluctuations attain increasing amplitude as 

 the age of the plant increases. We are led therefore now to attempt to 

 correlate these fluctuations with changes in environmental conditions. 



Table I. — Unit Leaf Rale for Jive varieties of maize grown at Poppelsdorf 



in the year 1875. 



