ANIMAL PHYSIOLOGY. 359 



I have thought that one of the most curious and 

 striking examples of the adaptation of means to 

 ends, all tending to the good of man, might be 

 found in the food of birds. This, I presume, is 

 very well known in the common species as the 

 Corvidae though I am not aware that the food 

 of the migratory species has been sufficiently 

 attended to. Has any one examined the stomach 

 of young Cuckoos, and that of their foster-dams ? 

 Has any one shewn why the old cuckoo cannot 

 or will not feed her offspring ? Would not a 

 higher animal than the cuckoo, nay, even the 

 human animal, quit her young if the means of 

 supporting and nurturing it were utterly to fail ? 

 Yet the conduct of the cuckoo, that " rude bird of 

 hate," as Milton calls it, is still a mystery, and will 

 be so, till anatomical inquiries are pursued in con- 

 nection with the habits of animals. The hyberna- 

 tion of animals is another subject of very curious 

 import, connected, as it is, with deep questions in 

 physiology, and remarkably interesting in relation 

 to food and climate. 



That the peculiar food of some animals is made 

 subservient to the benefit of man, and that diges- 

 tion does not always destroy its vivifying princi- 

 ple, cannot admit of a doubt. For instance, many 

 birds feed on the spawn of fishes, and this will 

 account for fish being found in great variety, in 

 lakes and pools on the tops of mountains and 



