2l8 



BOTANICAL GAZETTE 



[march 



for the next 37 days. Though still in evidence at the end of that 

 time, we may infer that the ring was to all purposes complete. 



The contents of table H are presented in graph 2, where the 

 abscissas represent the diameter increase of new growth and the 

 ordinates 8 day periods. It is to be seen from both the table and 

 the curves that in the long run the cambium in all parts of the tree 

 tends to even up irregularities which arise from different growth 

 intensities. If growth is sluggish at one place in the bole and rapid 



8* IZ 



One space = 8 days 



/6 



20 



Graph 2. — Curves of growth amount, tree I, 1913 



in another during a given period, the pendulum of growth intensity 

 swings to the other extreme in the next period and evens up the 

 disparity. 



The irregularities of growth are manifested not only in the 

 actual dimensions of the new formed tissues, but in the number of 

 new xylem elements as well. If careful average counts of new 

 formed tracheids are made, and these compared with the average 

 number of tracheids at that point in the preceding ring, irregularities 



