98 THE METHOD OF DARWIN. 



animal body also, it can scarcely be doubtful 

 that, in spite of incomplete knowledge, the 

 assumption is nevertheless warranted that pep- 

 tonizing ferments are perhaps universally dis- 

 tributed in plants." 1 "Attention was first 

 drawn to the occurrence of peptonizing fer- 

 ments in the vegetable kingdom by the re- 

 markable phenomena observed in the so called 

 insectivorous plants." By analogical reasoning 

 a whole new field of study was opened ; a new 

 view of the powers of plants was gained, and a 

 much closer analogy between plant and animal 

 functions was established. But if recent studies 

 are taken into account, the question may be 

 raised whether this stupendous analogical struc- 

 ture has not been undermined. Tischutkin 

 contends that the "digestion" of insectivorous 

 plants is not accomplished in the same way as 

 in animals, but is due to bacteria; that the 

 pepsin of the leaves is not a secretion of the 

 plant, but a by-product of the activity of the 

 bacteria. 2 He proves that bacteria capable of 

 dissolving egg albumen are always present in 

 the secretion of the leaves; that they come 

 principally from the air, that the plant only 

 furnishes a medium for them to live in, that 



1 Sachs, Physiology of Plants, p. 344. 



2 Berichte der Deutschen Botanischen Gesellschaft, 1889. 



