1128 
Journal of Agricultural Research 
Vol. XXXI, No. 12 
the same age, and obviously volume growth, which is a complex of 
these four factors plus form factor, must also culminate. 
An examination of the volume curves (figs. 1 and 7) and of periodic 
annual increment (fig. 8) indicates that the better the site the earlier 
is the culmination of periodic annual increment. This seems to be 
in line with European and American observations. 
■40 60 80 100 120 140 160 180 
A6E OF OOMINANTS AT BREAST HEIGHT, YEARS 
Fig. 2.—Basal area per acre on age 
A study of the basal area curve (fig. 2) shows about equal inter¬ 
vals between sites, whereas in yield the interval between sites in¬ 
creases from poor to good sites. As far as a look into published data 
has shown, these tendencies seem to be in harmony with the results 
of more exhaustive work elsewhere. Of course these apparent 
agreements between the present study and other work do not neces¬ 
sarily prove anything. They may perhaps indicate that the method 
