INFUSORIES. 159 



with the sap in vegetables, 1 and are found in the 

 blood and excretions of animals, 2 who knows but 

 they may act an important part in the animal 

 frame ; somewhat similar to what devolves upon 

 the larves of certain insects, with regard to stag- 

 nant waters, they may be depurators where they 

 are thus employed, and contribute to preserve a 

 healthy action. It is true, as far as vegetables 

 are concerned, especially grain, they appear to 

 destroy, where they take up their residence, but 

 when we discover the same or similar species, in 

 sour paste or vinegar, they seem destined to con- 

 sume substances that cease to be wholesome ; and 

 in fact, in all fluids, in which they usually so 

 abound, they may be destined to fulfil a similar 

 office, and it is a remarkable circumstance in 

 their history confirmatory of this idea : that 

 these animals, though animation in them is 

 often suspended for a long time ; when they 

 swarm in infusions, having fulfilled their office, 

 perish in a few days. 



It is probable that in the waters of our globe 

 an infinity of animal and vegetable molecules 

 are suspended, that are too minute to form the 

 food of even the lowest and most minute animals 



i Mr. Bauer found Vibrio Tritiri, in the stalk as well as in the 

 ear and grain of plants of wheat, which were raised from seeds 

 inoculated with it. Phil. Trans. 1823. 3. 



- See above, p. 152. 



