[Vol. 6 



134 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



tures of Polystictus versicolor to which bacteria were added, 

 in all cases lost from two to three times more weight than was 

 lost by pure cultures of the fungus. Bacterium mycoides was 

 the only bacterium found in the culture bottles at the end of 

 the period of incubation. 



SERIES D: DOUGLAS FIR 



Lenzites saepiaria caused the most rapid rate of decay of 

 Douglas fir. The addition of bacteria to cultures of Fomes 



Lenzites saepiaria caused no apparent change 



the rate of decay. Cultures of P 



to 



which bacteria were added lost from five to ten times as much 

 weight as did cultures of the fungus alone. Bacterium 

 mycoides was the only bacterium found in the cultures at the 

 end of the period of incubation. 



Summary 



The experimental results obtained may be briefly summa- 

 rized as follows : 



1. When wood is sterilized by autoclaving it undergoes cer- 

 tain changes which must be considered when using wood for 

 experimental purposes with wood-decaying fungi. Among 

 these changes are: (a) a change in color; (b) an increase in 

 the amount of reducing substances in the extract; (c) an 

 increase in the acidity of the extract; (d) an increase in the 

 hydrogen ion concentration of the extract; (e) a change in re- 

 sistance towards decay. 



2. Cellulose-dissolving bacteria play no important part in 



the decay of wood under natural conditions. 



3. The results from the decaying experiments tend to indi- 

 cate that the rate of decay may be materially increased by the 

 presence of the ordinary saprophytic bacteria. 



4. The influence of bacteria on fungi with reference to the 

 rate of decay induced by the fungi varies with the different 

 fungi on different woods. 



5. Further experimentation along this line is essential. 



