96 



SCIENCE 



[N. S. Vol. XXXIV. No. 864 



sulphuric acid solution stained as readily as 

 the controls dipped in water. 



Eed gum and yellow pine sap boards dipped 

 in a hot 7 and 8 per cent, solution of sodium 

 carbonate and a hot 8 and 10 per cent, solu- 

 tion of sodium bicarbonate did not stain. 



After these laboratory experiments, the ex- 

 periments with the boards was repeated in the 

 field. That with the yellow pine in a lumber 

 yard in Louisiana from which the yellow pine 

 used in the laboratory had been received. 

 The red gum experiments were made in a 

 hardwood mill in Mississippi from which the 

 red gum boards experimented with came. In 

 the field experiments the sodium carbonate 

 used was the commercial soda ash, and the 

 sodium bicarbonate the Thistle Brand Soda. 



The tests were as follows: 



In a Louisiana lumber yard where the pine 

 boards were staining just where the boards 

 crossed in the open stack, the remainder of 

 the boards clean. Dry weather. 



Green yellow pine — 



5.3;^ sodium carbonate 2,184 ft. B.M. dipped. 

 4:^ sodium bicarbonate 3,136 ft. B.M. dipped. 



The treated lumber was stacked wet one 

 board on top of the other, and held for ob- 

 servation for seventeen days. The boards re- 

 mained unstained. 



In a Mississippi lumber yard where the 

 stacked boards were staining. Eainy weather. 



Green red gum — 



8^ sodium carbonate 3,012 ft. B.M. dipped. 

 11^ sodium bicarbonate 3,000 ft. B.M. dipped. 



The treated lumber was stacked wet one 

 board on top of the other, and held for ob- 

 servation fourteen days. Some of the sodium 

 bicarbonate boards were stained in spots. A 

 very few of the boards dipped in sodium 

 carbonate were stained on the ends. It was 

 found that the percentage of alkalinity of the 

 solution in the dipping vat was the same or 

 was a little greater at the end of the " day's 

 run " than at the beginning. 



Briefly stated the results of the field experi- 

 ments were as follows : An 8 per cent, solution 

 of Na^COj was as effective as 11 per cent. 

 HNaCOs. These soda solutions prevented the 



blue stain on red gum when the weather was 

 rainy. In dry weather 5 per cent. Na^COj 

 and 4 per cent. HNaC03 kept yellow pine 

 boards clean. 



In these experiments, laboratory and field, 

 the blue staining fungus showed itself sensi- 

 tive to alkalies in the medium on which it 

 grew. The amount of alkalies necessary to 

 inhibit the growth of the fungus varied with 

 the substratum. An increase in the acidity 

 of the medium did not prevent fungus growth. 

 Freshly cut red gum and yellow pine sap 

 boards required 8 per cent. Na^COj or 10 per 

 cent. HNaCOj to prevent them from being 

 stained when the blue-stain fungi were grow- 

 ing vigorously. 



Considering that the blue-stain fungus 

 thrives on a substratum containing a large 

 amount of acid and is sensitive to alkali in 

 the substratum, the acidity of the surface of 

 the boards just after being cut and the vigor 

 in the first growth of the fungus seem cor- 

 related. It is probable that a large amount 

 of acid is generated on the surfaces of the sap 

 boards when such strongly alkaline solutions 

 must be used to prevent the blue stain. 



This acidity of the boards, greater than 

 has probably been realized, may be the answer 

 to the problem as to why a soda solution of a 

 given strength is not always successful in 

 preventing the blue stain. A weak alkaline 

 solution may be successful in keeping the 

 boards clean when the atmospheric conditions 

 are not favorable to the growth of the fungus ; 

 when these conditions favor fungus growth, 

 the soda solution has not sufficiently neutral- 

 ized the board acids to stop the germination 

 of the spores and their mycelial growth. 



A greater resistance to the alkali in the 

 medium was shown by the spores of Ceraios- 

 tomella than by the mycelium. If this is the 

 case with the wood-staining fungi, it is ad- 

 visable when determining the value of wood- 

 impregnating materials, to test them with the 

 spores of the wood-destroying fungi, not 

 alone with the mycelium as has generally 

 been done hitherto. OAEOLmE Eumbold 



Missouri Botanical Garden, 

 St. Louis, Mo. 



