EVALUATION OF WOOD PRESERVATIVES 129 



minutes. The wood was inoculated by placing a piece of a culture of 

 Coniophora cerebella, grown on agar medium, directly on the wood. Bre- 

 azzano states that the wood was kept moist enough because of the water 

 in the sand, that the fungus grew luxuriantly, and that ''the development 

 of the fungus was evidently at the expense of the wood, since no other 

 nutritive substance was at its disposal." 



He used blocks cut from treated beech ties. The fungus grew readily 

 and he concludes that the treatment was not effective. He ends this 

 early report with the statement: 



"... If the experiment is carried on under carefully defined conditions 

 the various methods proposed for immunizing woods can be judged all 

 by the same standard." 



Breazzano presented his method at Pisa in 1919, and m 1922^^ the 

 principles of the sand-block culture were proposed as standard procedure 

 (for Italy) for evaluating wood preservatives. Precise directions were 

 given for the whole test technique, Avith important modification of the 

 cultures, as indicated in the steps outlined below: 



1. SteriUze by dry heat, at 180°C, "soyka" boxes 8 cm in diameter 

 and 4 cm in height "in which is first placed a layer of sand 1 cm deep". 



2. Prepare blocks of wood — treated and untreated — 4x4x2 cm, 

 cutting them so that the broader faces will be transverse sections; and 

 place these test blocks broad face down on the sand. 



3. Sterilize at 100°C for one hour. 



4. After steriHzing and cooling add sterile water in an amount that 

 will be slightly in excess of what the sand can absorb. 



0. After the wood blocks become moist plant Coniophora cerebella — 

 without carrying over any agar medium with the transplant. 



6. Incubate the "soyka" box cultures in a covered crystalUzing dish 

 in a dark place for one month at 20-25°C; and "Take care that in this 

 time the water which the sand absorbs does not evaporate completely, 

 and add sterile water when necessary." 



At the end of the test the wood blocks were to be examined for decay; 

 and if there was any doubt the wood was to be sectioned and examined 

 microscopically for the presence of wood-destroying fungus hyphae 

 (threads). 



In retrospect the subsequent changes involving the use of soil instead 

 of sand, and in the testing of blocks specially treated for the experiment, 

 seem hke refinements of Breazzano's methods. He later shifted to the 

 use of very thin pieces of treated wood for his test specimens,^ ^^ severely 

 criticizing the agar-block method that grew out of the BerUn conference 

 as time consuming and inaccurate (loc. cit.). 



