1919] 



SCHMITZ STUDIES IN THE DECAY OF WOOD 111 



RELATION OF BACTERIA TO THE RATE OF DECAY INDUCED BY 



FUNGI UNDER LABORATORY CONDITIONS 



It is possible that even though the cellulose-dissolving bac- 

 teria play no part in the decay of wood under natural condi- 

 tions, the ordinary air, soil, and water forms, so universally 

 found in connection with decaying wood, may have an impor- 

 tant indirect influence on the rate of decay caused by fungi. 

 This may come about by these organisms changing the reaction 

 of the substratum in such a manner that it may be more or less 

 favorable to the optimum development of the fungus ; or it is 

 also quite possible that in their metabolism they may utilize 

 some of the hydrolytic products produced by the fungus, an ac- 

 cumulation of which might be partially toxic to the fungus. In 

 order to determine whether or not this is true, pure cultures 

 of bacteria were added to pure cultures of different fungi and 

 their effect, if any, on the rate of decay noted. 



Methods and materials. — Approximately equal amounts of 

 sawdust were placed in clean weighed 125-cc. wide-necked bot- 

 tles. The bottles and contents were placed in a hot-air oven 

 and dried to constant weight at a temperature of 90° C. and 

 weighed again. Approximately equal amounts of water were 

 added to each flask and they were then plugged and sterilized 

 at fifteen pounds for twenty minutes. Every effort was made 

 to have conditions as nearly identical as possible in each bot- 

 tle. Each was inoculated with a wood-destroying fungus, and 

 after the wood was well infected bacteria were added and the 

 rate of decay determined by the loss in weight of the culture 

 bottles after six months. 



The experiments were conducted with four species of com- 

 mercial woods, Douglas fir (Pseudotsuga taxifolia), western 

 hemlock (Tsuga heterophylla), white ash (Fraxinus sp.), and 

 red oak (Quercus sp.). Heart-wood was used in each instance. 

 The Douglas fir and western hemlock wood were obtained from 

 freshly sawed logs. The white ash and red oak were pur- 

 chased from lumber dealers and were in all probability air- 

 seasoned. The sawdust was prepared as previously dis- 

 cussed. 



