Chap. I. FOOD AND DIGESTION. 37 



Leon Fredericq states* that the digestive 

 fluid of worms is of the same nature as the 

 pancreatic secretion of the higher animals ; 

 and this conclusion 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 live 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 known that all other nutri- 

 tious substances are almost completely with- 

 drawn from leaves, shortly before they fall 

 off. 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 Zoologie experimentale/ torn. vii. 1878, p. 394. 



t On the action of the pancreatic ferment, see * A Text-Book 

 of Physiology/ by Michael Foster, 2nd edit. pp. 198-203. 1878. 



% Schmiilewitsch, * Action des Sues digestifs sur la Cellulose.* 

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

 1879. 



