8 BULLETIN 1112, U. S. DEPARTMENT OF AGRICULTURE. 
and at every 8 feet above this point. The measurements were 
recorded by 5-year periods instead of by decades, as is the usual prac- 
tice in complete stem analysis. The trees were selected as nearly as 
possible from the same site, kind of stand, and the same age and 
crown classes. Only those trees free from abnormalities or other 
possible causes of deterioration or conditions deterrent to their 
growth were studied, thus permitting only two variables to enter 
into the results, the age of the tree and the degree of mistletoe infec- 
tion. The classification of the tree according to degree of infection 
represents the consensus of opinion of three different observers. 
The basic data for each of the individual felled trees which were 
analyzed to show the effect of mistletoe on the growth and seed pro- 
duction of western yellow pine have been arranged in Table 7, accord- 
ing to the age of the trees. In compiling the stem analyses the data 
for each tree were computed separately. The diameters and heights 
of each tree for each fifth year, dating back from the year of analysis, 
were correlated with age in growth-analysis diagrams, from which 
the dimensions of each tree for each integral 5 years of age or quin- 
quennium were read. 
TaBLE 5.—Comparison of the average diameter growth or accretion of 33 standing black 
jacks, for a 5-year period, at 4.5, 17, and 33 feet from ground, grouped according to 
degree of mistletoe infection. 
Diameter outside bark. Accretion, 1911-1916. 
Degree of 1911 1916 Periodic. Periodic annual. Basie 
infection. z 
17 33 4.5 17 33 4.5 17 33 4.5 17 33 
feet. | feet. | feet. | feet. | feet. | feet. | feet. | feet. | feet. | feet. | feet. 
- In. In. In. In. In. In. | In. | In. | In. | In. | In. | Trees. 
Orr ee: 15. 28 | 12.69 |} 19.03 | 16.30 | 13.71 | 1.10 | 1.02 | 1.02 | 0.22 | 0.20 | 0.20 16 
p aay ag ge 19.59 | 14.14 | 23.40 | 20.85 | 15.25 | 1.15 | 1.26 | 1.11 A or 225. ees e2 4 
sa Se 13.20 | 8.65 | 16.78 | 13.81 9. 46 . 86 .61 81 ahi le sZt z 
RN ee 14.42} 9.19 | 17.15 | 14.64] 9.31 «68-1 «22 tz. ts. 14 - 04 . 02 6 
TABLE 6.—Comparison of the total volume growth or increment of 33 standing black 
jacks, for a 5-year period, grouped according to degree of mistletoe infection. 
Total volume. Increment, 1911-1916. 
Degree of infection. Basis. 
1911 } 1916 Periodic. Periodic annual. 
| er fc | aS 
Cubic feet. | Cubic feet. | Cubic feet. | Cubic feet. | Per cent. Trees. 
919. 76 1, 047. 40 127. 64 2520S 2. 78 
oe See 2 eee ee eee 359. 07 410. 65 51.58 10. 32 2. 87 4 
ees PH TAL HS kL eee 286. 83 316. 08 29. 25 5. 85 2. 04 7 
5.2.0. et el Sf RR ER RE ee 262. 65 273. 97 11.32 2. 26 - 86 6 
