Chap. I. FOOD AND DIGESTION. 37 



Leon Fredericq states* tliai tlie digestive 

 fluid of worms is of the same nature as the 

 pancreatic secretion of the higher animals ; 

 and this conchision agrees perfectly with the 

 kinds of food which worms consume. Pan- 

 creatic juice emulsifies fat, and we have just 

 seen how greedily worms devour fat ; it 

 dissolves fibrin, and worms eat raw meat ; it 

 converts starch into grape-sugar with wonder- 

 ful rapidity, and we shall presently show that 

 the digestive fluid of worms acts on starch. f 

 But they hve chiefly on half-decayed leaves ; 

 and these would be useless to them unless they 

 could digest the cellulose forming the cell- 

 walls ; for it is well kiiown that all other nutri- 

 tious substances are almost completely with- 

 drawn from leaves, shortly before they fall 

 ofi^. It has, however, now been ascertained 

 that cellulose, though very little or not at all 

 attacked by the gastric secretion of the higher 

 animals, is acted on by that from the pancreas. J 



* * Archives de Zoolouie expe'riinentale,' torn. vii. 1878, ]). 394. 



t On the action of the pancreaiio ferment, see ' A Text-Book 

 of Pliysiology,'by Michael Foster, 2nd edit. pp. 198-203. 1878. 



X Schtiiulewitbcb, 'Action des Sues digestifs sur la Cellulose.' 

 Bull, de I'Acad. Imp. de St. Pe'teisbourg, torn. xxv. p. ,549. 

 1870. 



