H. S. REED 



549 



Group (a) contained nineteen trees, Group (b) fifteen trees, and Group 

 (c) twenty-five trees. 



%^ The mean height of the selected trees on the several days of measure- 

 ment is represented graphically in Fig. 2. The data show that Juglans 

 nigra grew quite uniformly from the commencement of the measure- 



TABLE II, 

 Mean Height of Walnut Trees. 



ments on April 17 until about June 19 (the 62nd day). Between 

 June 19 and August 6 (between the 62nd and 110th days) growth was 

 considerably more rapid, but after August 6 growth gradually dimin- 

 ished until it ceased about September 3. 



The mean growing period of this group of trees was 124 days after 

 April 17, The coefficient of variability of the population at each 



