394 



Dr Christison on the 



b 



increase, and in only seven was the maxiuuim less than 

 twice as great as the niinimuni. Even in the tree which 

 varied least, the proportion of the maximum to the minimum 

 was as 4 to 3, while in that which varied most it w^as as 

 65 to 0. The maximum and minimum increase in these two 

 catesories of trees is here siven. 



Thirty-four Decidvoux^ Trees Measured. 



A similar investigation of the evergreen trees yields quite 

 as extreme results. Of twenty-nine availahle trees, in eight 

 the annual maximum was more than four times greater than 

 the annual minimum, and in only ten was the maximum less 

 than twice as great as the minimum. In the tree which 

 vaiied least the proportion was as 9 to 7, while in that which 

 varied most, discarding trees wliich were killed, it was as 

 IG to 1. 



Tweniy-nine Evergreen Trees measured. 



