36 College of Forestry 



disappear with the completion of tlio decay. Von Schrenk 

 (1914), in discussing- tlie decay of lilac {Syringa vulgaris 

 L.) stems by Polystictus versicolor ( J^. ) Fries, says that the 

 brown substance is destroyed ultimately when the decay nears 

 completion. The decomposition products, which have been 

 shown to originate with the advancement of the fungus 

 through the sound wood, are likewise destroyed by the fungus 

 upon the completion of the decay in a given area and no 

 traces of them are left in the completely decomposed wood. 

 Evidence of this is to be found in that the decomposition 

 products at first are always present in a thin zone between 

 the decayed and undecayed wood. Later when the decay 

 spreads from several centers the decomposition products 

 collect in thin zones between the various areas of wood 

 in diiferent stages of decay. Thus the constant associa- 

 tion of these blackish zones of decom])osition products with 

 that portion of the sound wood bordering upon the decayed 

 wood is to be explained by the fact that they are destroyed 

 upon the completion of the decay within any one area but 

 new ones constantly form from the sound wood as soon as 

 it is attacked by the advancing fungus. 



There remains to be considered the identity of those sub- 

 stances from which the decomposition products are formed, 

 the chemical changes taking place, and the final chemical 

 nature of the brown deomposition product. The present study 

 has not been sufficiently extensive to answer these questions 

 fully. Here we are entering a little known field since, even 

 at the present time, but little has been achieved as to the 

 chemical compositiou of sound wood and virtually nothing 

 concerning the chemical changes Avhich accompany its decay. 



It is evident, however, that the cell contents and possibly 

 certain other substances originally combined with cellulose 

 and ligiiin to constitute the cell wall furnish the formative 

 material which, through oxidation in the presence of mois- 

 ture, coagulates to thick drops and gives rise to the decom- 



