1122 
Journal of Agricultural Research 
Vol. XXXI, No. 12 
In the first place there was practically no true second growth in this 
locality. Almost the entire area was virgin forest in which no cutting 
at all had been done. Secondly, only one mill was cutting in the 
area, so that the opportunities for laying out plots and for obtaining 
taper measurements were exceedingly limited. Further, no volume 
tables were in existence which would be suitable for immature yellow 
pine and white fir (Abies concolor ), that is, for trees up to about 150 
years old; and therefore as an accompaniment to the main study it 
was clearly necessary to collect data for the construction of such 
tables. 
The virtual absence of true second growth made it compulsory to 
select even-aged groups of the younger age classes growing within 
the virgin forest, such as commonly occur where fire or insects have 
created small openings within the main stand and where reproduce 
tion has come in and made a fully stocked stand. These groups by 
no means form an ideal substitute for true second growth, for it is 
quite certain that the mature trees surrounding them have influenced 
the growth of the younger classes, probably to a considerable extent. 
A further disadvantage is entailed by the fact that these even-aged 
groups within the virgin forest are commonly rather small and it is 
often almost impossible to lay out an isolation strip surrounding the 
f )lots. In the majority of cases, in order to obtain plots of a satis- 
actory size, it was necessary to include practically the entire group 
of young trees, every effort being made to keep the boundary lines 
sufficiently far out from the edge of the crowns so that too high an 
apparent yield would not be secured. With the great majority of the 
plots, also, the usual rectangular form could not be maintained, for 
the boundary lines had to conform to the shape of the plot on the 
ground. 
The absence of cuttings and the undesirability of slashing down 
too many trees, together with the fact that cutting of trees on every 
plot would have slowed down the work very greatly, made it neces¬ 
sary to obtain age determinations by means of the increment borer. 
Cores were taken at breast height on several trees on each plot and 
the usual stump analysis measurements made on these cores. In 
selecting trees for boring, both large and small trees on each plot 
were taken, to be certain that the plot was even-aged and not of 
several ages. 
In order to determine the number of years required by the trees 
to reach breast height, seedling analyses were made on or near 
practically every plot measured. The seedlings were selected, as far 
as possible, from those growing in small openings in the stand and 
apparently were dominant. Toward the end of the work, when an 
opportunity arose to lay out plots in the true second growth itself, 
similar seedling analyses were made in large openings created by 
clear cutting in the virgin stand. In this way a very good idea was 
obtained of the difference in rate of seedling growth in the virgin 
stand, where unquestionably the seedlings are badly oppressed, and 
in the open under conditions such as would follow cutting of the old 
timber. 
In the determination of heights it was decided to measure only 
one or two trees in each of the four dominance classes (dominant, 
codominant, intermediate, and suppressed), rather than to attempt 
