1919] 



SCHMITZ STUDIES IX THE DECAY OF WOOD 117 



distilled water had not killed the organisms. In the case of the 

 controls and bottles which contained the fungi alone a similar 

 amount of sterile distilled water was added so that the mois- 

 ture conditions in all the culture bottles would be the same. 



After all of the culture bottles were inoculated with the de- 

 sired organisms the cotton plug of each was covered with two 

 thicknesses of paraffined tissue paper to avoid excessive evap- 

 oration from the flasks, the paper being secured by means of a 

 rubber band. This did not make an air-tight covering, but in 

 most cases the cultures remained sufficiently moist without 

 watering throughout the period of incubation. In the few 

 cases in which additional watering was necessary effort was 

 made to keep the moisture conditions similar to those of the 

 other culture bottles. 



The cultures were then removed to a very humid rotting-pit 

 with a temperature varying from 22° C. in summer to 35° C. 

 in winter. The period of incubation in all cases was six 

 months. 



At the end of the period of incubation small particles of 

 sawdust, such as would adhere to a moist sterile platinum 

 needle were transferred to sterile potato agar slants in order 

 to determine whether or not the bacteria were still alive. The 

 plugs were then removed and the culture bottles again dried to 

 constant weight in the hot-air oven at a temperature of 90° C, 

 weighed, and the loss in weight determined. 



In all cases the rate of decay is based on the loss in weight 

 of the culture bottles during the period of incubation. Each 

 set originally contained ten cultures but some were thrown out, 

 due to infection of the fungus not taking. The average loss in 

 each set was determined and taken as the basis of comparison 

 between the various sets. 



DESCRIPTION OF CULTURE SERIES 



Four series of cultures were prepared: series A, of red oak; 

 series B, of white ash ; series C, of western hemlock ; and series 

 D, of Douglas fir. 



Culture bottles from which transfers were made to deter- 

 mine the presence or absence of bacteria at the end of the 



