percentages of sulfur were used: -10%, .25%, .50%, '75%, 1.0%, 

 2.0%, and 5.0%. Mycelium from a pure culture of Stereum was trans- 

 ferred to sterile tubes containing the nutrient-agar, nutrient-creosote- 

 agar, and the nutrient-sulfur-agar. The results, in brief, showed that the 

 fungus grew equally as well on the sulfur medium of the lower percent- 

 ages as on the nutrient agar alone. A very slight reduction in the vigor 

 of growth was evident in the tubes containing the highest percentage of 

 sulfur. The fungus failed to grow on the creosote mixtures which con- 

 tained .50% of creosote and grew rather feebly on those of lower per- 

 centages. 



A number of two-litre flasks were partially filled with the Alnus- 

 Salix tea agar, into which sticks of Alnus and Salix w r ere placed in such 

 a manner that portions of the sticks extended considerably above the 

 surface of the agar. Into each of these flasks were placed small blocks 

 of Alnus oregona and of Pseudotsuga taxifolia which had previously been 

 impregnated with one-third pound of sulfur per cubic foot by precipitation 

 from ammonium polysulfide. Mycelium from a pure culture of Stereum 

 was then transferred to each flask. The fungus grew vigorously over the 

 surface of the culture and on the blocks of impregnated wood. After a 

 period of twelve weeks the impregnated blocks were removed from the 

 flasks, sectioned on a microtome and treated with a differential stain for 

 fungus and host tissues. The stain was one kno\vn as Pianeze I lib.* 

 The formula is as follows: 



Malachite Green 0.50 grams. 



Acid Fuchsin 0.10 grams. 



"Martius Gelb" 0.01 grams. 



Water, Distilled 150.00 c. c. 



Alcohol, 95% 50.00 c. c. 



The wood sections are washed in water or alcohol, stained for 15-15 

 minutes in the undiluted mixture and the excess stain removed in w r ater. 

 The sections are decolorized in 95% alcohol to which a few drops of 

 hydrochloric acid have been added. The lignified cells of the host are 

 stained green, and the unlignified cells of the fungus are stained a deep 

 pink. An examination of the stained sections showed that the mycelium 

 of the fungus had penetrated the tissues of the Alder in nearly every 

 case to a distance of from four to twelve millimeters from the outer surface 

 of the block. The presence of the mycelium in the tissues of the Douglas 

 Fir block was doubtful, the results of the staining being less definite than 

 in the Alder. 



The results of the foregoing experiment would seem to indicate that 

 sulfur precipitated in the tissues of Alder from ammonium polysulfide has 

 riot sufficient toxicity to inhibit the growth of the mycelia of Stereum 

 through the wood cells. In order to get more complete results, experi- 

 ments similar to those outlined herein are being conducted, using dif- 

 ferent species of fungi and different species of wood. It is known that 

 marine borers are not destructive in water containing much sewage and 

 experiments are under way to determine the effect of sulfur as a pre- 

 ventative against destruction of wood in salt water by marine borers. As 

 sulfur is comparatively cheap, and as more favorable results may be ob- 

 tained with heavier treatments, it is possible that sulfur may be used to 

 some extent as a commercial wood preservative. 



*Vaughan, R. E. Annals of Missouri Botanical Garden. 1:241-42. May, 

 1914. 



48 



