4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO7 



In another experiment, one dish of seeds was placed in a 13-liter 

 desiccator with three pieces of spruce board (total 358 g.) and a 

 second set enclosed in a similar container with an equal weight of 

 small chips (prepared by running a piece of the same board over a 

 planer set at 1/16 inch) which of course possessed a very much 

 greater exposed surface. Both sets were inhibited equally, suggest- 

 ing that the degree of inhibition is related to weight or volume of 

 wood rather than to surface. No inhibition was found when only 

 one-ninth the weight (40 g.) of chips was present. 



Table i. — Inhibition of oat germination by emanations from various species 

 of wood (see also pi. 5) 



Relative 

 effectiveness Wood 



I Tulip poplar 



2 Spruce 



3 Red oak 



4 White oak 



5 Black walnut 



6 Douglas fir (plyboard) 



7 Poplar 



8 Eastern red cedar 



9 Mahogany 



10 Black cherry 



Hardboard. — It remained to test the Masonite Tempered Presd- 

 wood ^ such as had been used in construction of the box in which the 

 inhibitory effect was originally observed. This material also was 

 found to produce a toxic emanation. 



IDENTITY OF THE INHIBITOR 



It is well known that autoxidation of unsaturated fats and of dry- 

 ing oils, such as are used in the formulation of varnish, gives rise to a 

 variety of volatile products (Friend, 1917; Hefter and Schonfeld, 

 1937; Gardner, 1914a; Vogel, 1930; Lea, 1938). Volatile com- 

 pounds have been shown also to be present in, or produced by, wood 

 and certain wood constituents (Wise, 1944; Schorger, 1917; King- 



s According to the manufacturer this material is made from exploded wood 

 fiber, chiefly of southern yellow pine. The lignocellulose fibers are refined, 

 felted, and pressed into board form and then impregnated with a resin compound 

 which is completely polymerized by heating. 



