[Vol. 6 



132 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



coli, B. vulgaris, B. prodigiosus, and B. vulgatus as the organ- 



isms. 



The results of the titrations, expressed in degrees of acidity, 

 Fuller's scale, are given in table xix. All series were run in 

 triplicate and the following results are the average of three 

 titrations : 



TABLE XIX 



THE EFFECT OF PURE CULTURES OF BACTERIA ON THE REACTION OF WOOD 



EXTRACTS 



Organism Red oak 



Western hemlock 



Douglas fir 



Control 



13.0 

 13.0 

 13.5 

 13.7 



13.3 



2.5 

 2.0 

 2.5 



3.0 



Bacillus coli 



3.2 



Bacillus vulgaris 



3.0 



Bacillus prodigiosus 



3-. 5 



Bacillus vulgatus 





3.3 



In the case of the red oak extract the end point could not be 

 exactly determined because of the dark color of the extract 

 which might account for the slight variations in the titrations. 

 It is evident therefore that these organisms do not change the 

 titratable acidity of the wood extracts to any considerable ex- 

 tent, if at all. 



Transfers made from the cultures at the end of thirty days ' 

 incubation to hard potato agar were negative in every case 

 indicating that the wood extracts were either toxic to, or 

 lacked some of, the necessary substances for continued growth 



y 



of the organisms. 



Discussion of Results 

 series a: red oak 



The rate of decay of red oak was comparatively slow with 

 the three fungi used. Lenzites saepiaria caused the most rapid 

 loss in Aveight in the culture bottles. In cultures first inocu- 

 lated with Fomes pinicola and subsequently with Polystictus 

 versicolor and Lenzites saepiaria the rate of decay was greater 

 than that caused by any of the fungi growing separately and 

 indeed greater than the combined rate of the three. In all 

 cases the rates of decay caused by the fungi alone were less 

 than those to which cultures of bacteria were added. With 

 Fomes pinicola the highest rate of decay was produced in cul- 



