EVALUATION OF WOOD PRESERVATIVES 453 



has varied almost as much as the test procedure employed. In a labora- 

 tory working plan for a study of the "Efficiency of Various Wood Pre- 

 servatives," with the subtitle ''The Efficiency of Various Wood Preserva- 

 tives in Resisting the Attack of Fungi in Pure Cultures," signed by C. J. 

 Humphrey, dated July 10, 1913, and approved by Howard F. Weiss, at 

 that time director of the young U. S. Forest Products Laboratory, 

 Humphrey proposed the use of eastern hemlock heartwood, cut into 

 pieces measuring 1}^ x 1}^ x 2 inches, which were to be treated and 

 quartered longitudinally "to reduce the size sufficiently to allow their intro- 

 duction into the (Erlenmeyer) flask.'' (Writer's italics.) 



Untreated wood blocks were to be used as culture media, and thirty 

 days after inoculation the test pieces were to be put into the flasks and 

 shaken up with the inoculated blocks. The test fungus was to be Lentinus 

 lepideus. The culture period was to be 9 months, with culture blocks and 

 mycelium "kept in a condition moist and warm enough for active 

 growth" throughout the test period. Coincidently, Humphrey^^ and his 

 colleagues were developing the broad foundation for the Petri dish tox- 

 icity test. The proposed wood block tests never reached a really satis- 

 factory experimental level for treated wood, although they were em- 

 ployed for comparative natural durability tests." 



Breazzano^"' ^^ in the same year experimented with blocks of beech 

 wood cut from treated ties and measuring about 9 x 2 x 1 cm. As has 

 been pointed out earlier in this paper he recommended blocks measuring 

 4 X 2 x 1 cm as a tentative standard, and later, in 1922, blocks 4x4x2 

 cm. were accepted as standard in Italy. ^ In the case of the latter the 

 larger faces were to be transverse faces, cut across the grain. 



Howe^^ reports tests of small sticks (blocks) of southern pine, measur- 

 ing % X % X 6 inches, that were treated with salt preservatives and later 

 inserted in "8-inch sterilized test tubes containing about 10 cc of standard 

 malt agar." He also used sets of four small sticks in Petri dishes, placing 

 them on 10 cc of nutrient agar medium that covered the bottom of the 

 dishes. The fungus used was called Fames annosus. To supplement these 

 tests he mixed ground-up treated wood in different concentrations with 

 agar media, and tested his mixes against this same Fames annosus and 

 a number of other wood-destroying fungi. 



Howe and Curtin^^ were working on a broad plan aimed at correlating 

 laboratory tests with test plot tests made, e.g., at Matawan, N. J,, and 

 with experience in line. 



Snell^°^ argued that one might obtain good growth by placing thin 

 blocks of wood in tubes with agar, but that the growth of the test fungus 

 on the agar and on the wood might be influenced by diffusion of the 



