870 JOURXAL OF FORESTRY 



gradual widening of a uniseriate ray or by the fusion of several smaller 

 ones, but by the abrupt cession of growth of other tissue and the de- 

 velopment of ray parenchyma." A. K. 



La Dema M. Langdon : The Ray System of Quercus Alba. Botanical Gazette, 

 vol. 65, 1918, pp. 313-323- 



UTILIZATION, MARKET, AND TECHNOLOGY 



Herbert Stone, author of "Timbers of Com- 

 Cause of merce and Their Identification," has ventured 



Durability upon some interesting hypotheses as to the cause 



of Wood of the relative durability of wood. He suggests 



that "durability may be an absence of germs 

 rather than a quality of a wood," but adds that it is the relative dura- 

 bility of woods placed under like conditions that is of practical interest. 

 By a series of logical steps, the conclusion is reached that "it is not 

 the lignin which is the resistant substance, but that some other sub- 

 stance is added to the perishable sapwood which converts it into durable 

 heartwood ; and may not this substance indeed be 'phlobaphene,' 

 known as red oak and used by fishermen to preserve sail-cloth, which 

 is said to be derived from tannin by further oxidation" ? 



Furthermore, decay cannot be due to oxidation, since perishable 

 woods may last indefinitely, exposed either to oxygen of the air or of 

 water, and, on the contrary, woods sealed away from oxygen often 

 perish rapidly. It is evidently produced by a fungus and also a microbe. 

 Bacillus amylohactcr, which attacks the intercellular substance and not 

 the lignin. 



In regard to the substantiation of Mr. Stone's hypotheses from a 

 chemist's standpoint, Dr. Hawley has kindly supplied the following 

 comments : 



Mr. Stone's article is admittedly a series of suggestions rather than 

 statements of fact. There are few of these which we do not believe 

 to be meritorious and some of the discussions give wrong impressions. 

 For instance, the question, "What is added to the perishable sapwood in 

 order that it may become durable heartwood ?" implies that the differ- 

 ence in durability is necessarily due to something added to the sap- 

 wood. A common opinion is that something has been removed from 

 the sapwood to make the heartwood more durable ; it is easy to con- 

 ceive that the liquid sap, the starch, and the other less stable constitu- 

 ents of the sapwood are particularly good foods for the fungi, and it 

 does not seem to be necessary to consider the addition of something 

 to sapwood to make it more durable. 



