CLEANLINESS. Ill 



which the dressing is said to be effected, they would 

 have seen at once that the theory is untenable, as the 

 quantity secreted in one day would scarcely suffice to 

 anoint a single feather, much less the whole. We 

 have just squeezed out all the oil contained in the 

 double rump-gland of a common wren, and found it 

 impossible to make it go over one of the tail feath- 

 ers. " One fact," says M. Le Vaillant. " is frequent- 

 ly sufficient to demolish a theory ;" and the fact that 

 the feathers of the rumpless fowls which have no 

 gland are as smooth and proof against rain as those 

 which possess the gland, furnishes a striking illus- 

 tration of the remark. 



The fact, however, is unquestionable, that birds 

 are sometimes seen pecking about the gland in ques- 

 tion. But the observing of a bird thus engaged, so 

 far from authorizing the received conclusion, might 

 have shown that the point of the bill could never 

 squeeze out enough of fluid for the purpose alleged. 

 The only legitimate inference would have been that 

 some slight pain or irritation had caused the bird to 

 peck the gland; and every schoolboy knows that 

 the canal of this gland often becomes obstructed in 

 his pet birds, and occasions a troublesome and some- 

 times fatal engorgement. 



The remark of Blumenbach that the gland is lar- 

 gest in aquatic birds, contains a generalization not 

 warranted by facts ; for grebes, divers, and such as 

 want tails, have the gland much smaller, though their 

 feathers are as smooth and as impenetrable by wa- 

 ter as those of the terns and the gulls which have 

 considerable tails. 



It is only requisite, indeed, for any one to watch a 

 bird preening its feathers, to be convinced of the fal- 

 lacy of the theory. We have attended for hours to va- 

 rious species of birds when thus engaged ; and so far 

 from constantly returning to the rump-gland, which 

 by the hypothesis would be indispensable for dress- 

 ing every successive feather, it is rarely visited at 



