1923] Dore-Miller: The Digestion of Wood by Teredo navalis 389 



hours, the alcohol evaporated off and the residual extract dried at 

 100° C. and weighed. 



7. Reducing sugars in alcohol extract. — The alcohol extract was 

 digested in about 25 c.c. of hot water, allowed to cool, and basic lead 

 acetate solution added until no further precipitation occurred. The 

 precipitate was filtered off and the clear solution deleaded with sodium 

 carbonate and filtered. The filtrate was neutralized with acetic acid, 

 made up to 100 c.c. and reducing sugars determined by the Munson 

 and Walker (1906) method, the cuprous oxide j^eing burned to cupric 

 oxide and weighed as such in the manner recommended by Davis and 

 Daish (1913] 



8. Hemicelluloses. — After the alcoholic extraction, the contents of 

 the thimble were transferred to a 300 c.c. Erlenmeyer flask and 

 hydrolyzed by digesting on the steam bath for three hours with 1 per 

 cent hydrochloric acid, the conditions being those proposed by Spoehr 

 (1919). The undissolved residue was filtered off and used for the 

 cellulose and lignin determinations. The filtrate containing the 

 hydrolyzed carbohydrates was neutralized with solid lead carbonate 

 and after removing the lead precipitate and deleading. the reducing 

 sugars Mere determine.! as described under "reducing sugars in 

 alcohol extract." 



Cellulose and lignin were determined upon separate portions of 

 "the residue remaining after the acid digestion for the removal of 

 hemicelluloses. 



9. Cellulose. — One portion of the residual material from the hemi- 

 eellulose determination was transferred to a weighed Gooch crucible 

 carrying a filtered disk of mercerized cotton cloth. Cellulose was 

 then determined by the chlorination method of Sieber and Walter, 

 which has been previously described by one of us (Dore, 1920a). 



When this method was applied to the ejected borings, it gave a 

 cellulose residue contaminated with a certain amount of non-cellulose 

 material that resisted chlorination. To correct for the presence of 

 this extraneous matter, the crude cellulose residue was weighed and 

 the cellulose dissolved out of the mixture by digesting overnight in 

 cold 72 per cent sulfuric acid. The mixture was diluted with water. 

 The undissolved non-cellulose residue was collected on the original 

 filter, washed, dried, and weighed. Its weight was deducted from the 

 weight of crude cellulose previously obtained, thus giving the weight 

 of true cellulose. 



10. Lignin. — Another portion of the residual material from the 

 hemicellulose determination was transferred to a 300 c.c. Erlenmeyer 



