340 



J. ARTHUR HARRIS 



the total number of rays in the series showing the lowest, and in one of 

 these showing the highest, correlation. 



23 25 27 29 31 33 35 36 



DIAGRAM 3. Regression of the deviation of the number of abnormal pedicels from 

 their probable value on the total number of pedicels in Spiraea. 



The standard deviations are : 



For 1909, &amp;lt;j, == 2.4691. 



For 1913, plant i, a g == 3.0527. 

 The regression equations are : 



For 1909, s == 1.3186 .0609 x. 



For 1913, ~ = 3.5036 .2212 _r. 



Illustration 6. Interrelationship of cotyledons and primordial leaves in a 

 race of Phascolus vulgaris highly variable in seedling characters 

 The ontogeny of the flowering- plant is usually divided into a primary 

 period of dependent development and a sharply separated period of inde 

 pendent growth. The leaf homologs which are developed during the first 

 penc 1 are usually of a very definite form and number, and frequently 



