W23] Dore-MiUer: The Digestion of Wood by Teredo navalis 395 



contain a considerably smaller proportion of cellulose to lignin than 

 the wood from which they were derived. If the cellulose figure is low, 

 the correct value can in.no case be higher than the total residue after 

 ehlorination (see table 5) and if the lignin is high, due to contamina- 

 tion with animal remains, the correct value can in no case be lower 

 than the lignin value given minus the total protein of the sample. 

 From tables 1, 2, and 5 we can then calculate the following: 



Maximum possible value for cellulose.. 

 Minimum possible value for lignin 



26.40 

 33.84 



14.20 

 27.51 



26.95 

 33.49 



In every case, the cellulose is materially less than the lignin, 

 whereas in the original wood the cellulose is about twice as much. It 

 appears impossible, therefore, to draw from the data any other 

 conclusion than that the cellulose partly disappears during digestion. 



We have previously referred to the possibility that the change in 

 the composition of the wood may occur after the material is ejected 

 by the borer. The compositions of the first and second samples of 

 borings in Series I furnish some experimental evidence on this point. 

 Although the second sample was purposely left in the sea water for 

 at least six months longer than the first, there was no significant 

 reduction in carbohydrate constituents (see table 3). In view of the 

 extreme resistance of wood to purely chemical action, and the absence 

 of known cellulose-destroj'ing fungi or bacteria in sea water, it seems 

 more reasonable to ascribe the loss of cellulose and other carbohydrates 

 to digestive action while in the body than to external agencies. 



Plankton is doubtless the principal food of Teredo as of other 

 lamellibranehs, and on account of its high protein content is probably 

 very suitable for purposes of growth and repair of waste. The teredo 

 which is boring, and consequently growing to fill the larger cavity, 

 requires, besides the protein food to provide for growth, a considerable 

 additional amount of food to furnish energy for its boring activities. 

 This energy could be supplied by the protein material of the plankton, 

 but much more efficiently by carbohydrates, inasmuch as these last 

 are completely oxidized and there is therefore no necessity of getting 

 rid of nitrogenous products. If, then, when its boring activities are 

 greatest, the teredo has available a considerable supply of carbo- 

 hydrate material to furnish the necessary energy and that available in 



