CHAPTER XII 



DURABILITY OF WOODS AND THEIR PRESERVATION 



AS FOSSILS 



One of the most important questions which enters into the 

 consideration of those who are called upon to employ timbers for 

 the various constructive purposes to which they are adapted, is 

 their ability to resist decay in its various forms, or their dura- 

 bility. Different species of woods vary widely in this respect, as 

 may be readily ascertained by consulting the data collected by 

 Professor C. S. Sargent in his Tenth Census Report upon the 

 Forest Resources of the United States, and as appears in the sec- 

 ond part of the present work. In general terms it is probably true 

 that the more resinous woods are more durable than those which 

 are less resinous, this being the direct result of the preservative 

 action of the resinous material, which is in itself highly resistant 

 to decay, and which further acts through its somewhat well- 

 defined antiseptic properties and therefore behaves toward the 

 general structure as a natural preservative, while it also excludes 

 water from the interior parts and thus tends to limit the opera- 

 tions of fungi. Thus it may be stated broadly that the resinous 

 conifers as a whole are more durable than the nonresinous 

 woods of the higher angiosperms. Or among the conifers them- 

 selves the hard pines are more durable than the soft pines, as 

 may be seen by a comparison of the southern pine (Finns palus- 

 tris) with the white pine (Pinus strobus). But apart from the 

 presence of resin, which may be localized or distributed through- 

 out the entire cellulose skeleton, it is altogether probable that the 

 durability depends to a very large extent upon inherent proper- 

 ties of the cell membranes which have become variously modified 

 in the course of growth and thus adapted to this end. Thus it has 

 already appeared (Chapter III, p. 48) that while the unmodified 



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