THE TRANSFORMATION OF FOOD 41 



acting on and digesting the bodies of the insects so 

 caught (Fig. 15). One instance must suffice to 

 illustrate this type of organism. On boggy hillsides 

 there is commonly to be seen a plant, known popu- 

 larly as " Sundew," from the glistening drops ter- 

 minating the numerous tentacles with which the 

 circular or ovoid leaves are covered and fringed. 

 Small insects, attracted by these drops and probably 

 also by the reddish colour of the leaves, are caught by 

 the secretion, which is sticky in character. The 

 contact with the insect induces a movement of the 

 tentacles towards the point of stimulation, so that 

 the insect's body becomes bathed in the secretion. 

 The contact also stimulates the glands at the ends 

 of the tentacles to secrete a ferment comparable with 

 pepsin, which attacks the proteids of the insect 

 body and digests them, the products being afterwards 

 absorbed by the leaf. The " pepsin " in the digestive 

 secretion of the Sundew acts only in an acid solution, 

 as in the case of the pepsin of the gastric juice of 

 the animal's stomach. 



