OF BIRDS. 413 



what means they are maintained in a period like 

 this is not quite manifest. The portion that they 

 require is probably small, yet it must be insect 

 food ; and the chats, larks, and grey wagtails, seem 

 busily engaged in providing for their wants upon 

 the furze sprays, amidst frozen grass, or upon the 

 banks of ditches and pools ; and as no insect but 

 the winter gnat is now found in such places, it is 

 probable that this creature, which sports in num- 

 bers in every sunny gleam, yields them in this 

 season much of their support. Some of the insec- 

 tivorous birds have at such periods no apparent 

 difficulty in supporting their existence, finding their 

 food in a dormant state in mosses, lichens, and 

 crevices of trees and buildings ; but for those 

 which require animated creatures, I am sensible of 

 none that are to be procured but this gnat, and it 

 possibly has been endowed with its peculiar habits 

 and dispositions for a purport like this. We have 

 many examples in nature of similar provisions, 

 wherein one race supports the existence and re- 

 quirements of another. The molluscae and insects 

 of the deep continue the life of some, the feeble 

 races of the air and waters maintain the beings of 

 others, and the beast of the wild seeks his food 

 amidst those which inhabit with him ; but where 

 this chain ends, human faculties will probably never 

 be able to ascertain, The remarkable fact which 

 our microscopes make known to us, that all infu- 

 sions of natural substances in water will produce 



