180 



EXPERIMENT STATION. 



[Jan. 



The difference in growth may be shown further by the differ- 

 ence in the length of internodes (or joints) in the wood. A 

 large number of measurements were made of the internodes of 

 one-year-old Avood, with the following results : — 



Length of Internodes. 



standard DeTiation 

 (Centimeters). 



On Americana, 

 On Wayland, . 

 On Marianna, 



6.85 



8.87 



10.47 



These figures show a much ranker, more vigorous growth in 

 trees on Marianna stocks than on the others. There is also a 

 greater amount of variation. The striking differences in the 

 growth of internodes, however, are again shown most forcibly 

 by representing all the measurements graphically, as is done in 



Fig- 4. _ 



This difference in growth comes out in every point where 

 measurements can be taken. For examj^le, the diameter of a 

 large number of branches was measured on two-year-old, on 

 three-year-old and on four-year-old wood. The average measure- 

 ments are shown below : — 



These measurements of the diameter of branches reveal once 

 more the fact that Milton plum trees grow much more vigorously 

 on Marianna roots than on Americana or Wayland. 



