[Vor. 5, 1918] 
114 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
and some of the resin was lost in sterilizing under steam pres- 
sure. The curves are corrected for this error. 
The curves in the three cases show that as the КӨНЕ in- 
creases the durability increases. In order to refer to some 
specific instances, examine plate 7, showing the cross-sections 
of the original shortleaf pine samples, and notice numbers 48 
and 53 in contrast with numbers 49 and 54. The former show 
a much higher percentage of dark summer wood and some- 
what narrower growth rings in the heart-wood than in the 
latter. In the table, numbers 48 and 53 show a loss in weight 
due to deeay of 2.85 and 1.88 per cent, respectively, and are 
relatively strong, while numbers 49 and 54 show a loss in 
weight from decay of 9 and 12.02 per cent, respectively, and 
are not nearly so strong as numbers 48 and 53. Other ex- 
amples, such as contrasting numbers 46 with 56, 52 with 47, 
ete., will show this same relation of strength and decay. For 
instance, in plate 8, showing the original samples of longleaf 
pine, number 63 has narrow rings with a high percentage of 
summer wood, characters which are conducive to strength, in 
contrast to number 65, which has broad rings with a low per- 
centage of summer wood. The strength tests show number 
63 much stronger than 65, and the decay tests show a loss of 
6.76 per cent in number 65 and 3.06 per cent in number 63. 
The same relation is shown when contrasting numbers 58 with 
61, 59 with 64, 60 with 66, eto. 
The results thus show that whether we are dealing with 
shortleaf pine or longleaf pine the stronger pieces of heart- 
wood are the more durable, and vice versa. "This, however, 
does not apply to sap-wood, as it seems to decay irrespective 
of the amount of summer wood and specific gravity, which 
materially influence the strength of yellow pine sap-wood. 
The writer wishes to express his appreciation to the Mis- 
souri Botanical Garden for the use of the laboratories; to the 
Southern Pine Association for providing funds which made 
this work possible; and to Dr. Hermann von Schrenk for sug- 
gesting this work and for his aid and interest. 
Graduate Laboratory, Missouri Botanical Garden. 
