1909.] 



PUBLIC DOCUMENT — No. 31. 



177 



easily demonstrated to the naked eye, cannot be so easily meas- 

 ured and recorded statistically. There is also a remarkable 

 difference in the marginal serrations in leaves from trees on 

 different stocks. Tracings of typical leaf margins are compared 

 in Fig. 2. By measuring the length of a large number of leaf 



Fig. 2. 



serrations in each lot, averages have been secured which will 

 serve for numerical conqjarison. In order to secure these meas- 

 urements with reasonable accuracy the leaf margins were con- 

 siderably magnified. On this account the units used in the 

 following comparison are arbitrary and need not be regarded. 

 (They were approximately one-eightieth of an inch.) 



Comimrison of Marginal Serrations. 



Arerage. 



Standard 

 Deviation. 



On Americana, 

 On Waylaiid, 

 On Marianna, 

 On peach, . 



38.00 

 35.08 

 31.02 

 34.75 



9.32 

 8.11 

 5.39 

 6.65 



