MINOR CARNIVORA. 127 



secretion. When a number of glands have been 

 excited, the secretion is so profuse that it trickles 

 down towards the incurved edges, but by the curva- 

 ture is prevented flowing off (fig. 18). 



The viscid fluid thrown off by the glands when 

 not excited by contact with insects, or other nitro- 

 genous substances, or fluids, is not in the least acid, 

 but when in contact with such substances is invariably 

 acid. This is an important fact to be borne in mind. 

 Flies caused the glands to secrete freely, the secre- 

 tion being acid. Small bits of roast meat always 

 caused much acid secretion in a few hours. Sugar 

 and starch caused considerable secretion, but it was 

 not acid. Bits of glass excited little or no secretion, 

 that small quantity not being acid. The secretion, 

 when containing animal matter in solution was soon 

 absorbed, causing the glands, which previously were 

 greenish and limpid, to become brownish, and contain 

 aggregated animal matter. No such effect was pro- 

 duced by other substances. The consequence of this 

 acidulation of the secretion, and the interpretation to 

 be attached to the change of colour and aggregation 

 of protoplasm in the glands, have already been 

 explained in the chapter relating to the sundews, and 

 therefore needs not to be repeated here. Suffice it 

 to say that they indicate a process analogous to 

 digestion. 



In the course of his experiments Mr. Darwin found 



