392 University of California Publications in Zoology [Vol.22 



The figures for benzene extract and alcohol extract appear to have 

 no special significance. The former represents resinous matter, the 

 latter tannins, coloring matter, and soluble sugars. None of these 

 except the soluble sugars can be regarded as having any nutritive 

 value for animals. The analyses show that extremely small amounts 

 of soluble sugars are present in wood and borings. Accordingly, 

 neither benzene soluble nor alcohol soluble constituents have been 

 considered in the recalculations. 



DISCUSSION OF RESULTS 



The data show that each of the samples of ejected matter contains 

 a much lower percentage of cellulose and a much higher percentage 

 of lignin than the wood from which it was derived. The figures for 

 hemicelluloses and furfural yield are less regular and not readily 

 comparable on the basis given. 



Inasmuch as it is extremely unlikely that any lignin was synthe- 

 sized during the passage of material through the digestive tract of 

 the animal, the increase in lignin is to be ascribed to concentration by 

 removal of cellulose and other wood constituents. Assuming that the 

 absolute amount of lignin remaining in the residue is the same as was 

 in the original wood, we may calcidate the percentage of the original 

 wood substance remaining in each of the three samples of borings by 

 determining in each ease the ratio of the lignin content to that of the 

 original wood. Thus the percentages of original wood substances in 

 the samples of borings are : 



Series I, sample 1 —— X 100% = 56.1% 

 54 . 55 



Series I, sample 2 — — X 100% =54.7% 

 55.97 



Series II, ^-^ X 100% = 50.9% 



54.66 



The data of table 3 have been recalculated so that the constituents 

 of the borings are expressed, not on 100 parts of borings, but on 100 

 parts of original wood, or, in other words, upon the number of parts 

 of borings corresponding to the percentages found in the preceding 

 paragraph. The results are given in table 4. 



