38 HABITS OF WOKMS. Chap. I. 



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 some forms of cellulose, though very 

 little or not at all attacked by the gastric 



* ■ Archives de Zoologie expe'rimentale/ torn. vii. 1878, p. 394. 

 When I wrote the above passage, I was not aware that Kruken- 

 berg (' Untersuchungen a. d. physiol. Inst. d. Univ. Heidelberg,' 

 Bd. ii. p. 37, 1877) had previously investigated the digestive 

 juice of Lumbricus. He states that it contains a peptic, and 

 diastatic, as well as a tryptic ferment. 



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

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



