Question of Birds' oiling their Plumage. 163 



bile in the living and healthy subject has no power of staining 

 what it touches : when the subject is dead, discolouration fol- 

 lows contact with it. Neither, supposing that his experiment 

 could be tried with the oil, and on the feather of a living bird, 

 would I attach much importance even to its success ; so very 

 much, in all probability, would depend on the birds volun- 

 tary obtaining the oil, and voluntarily applying it ; nor know 

 we, moreover, in what quantity the bird would apply it : and, 

 besides, birds may possibly, and probably do, secrete from 

 their mouths some liquid, which, mixed with the oil, may pro- 

 duce, as a compound, the effect we believe it to have. This 

 we have obviously no means of disproving, and, if necessary, 

 it may be the case. 



Lastly, Mr. Waterton contends, that the gland cannot con- 

 tain oil for the purpose of lubricating the plumage, because it 

 could not be applied by the bill to the back of its head (which 

 would therefore, I suppose, stand a chance of catching cold 

 in a shower of rain). Why, who ever said that it could be 

 applied by the bill to the back of the head ? or who ever saw 

 birds with their necks in the pillory, that they should not 

 bend their heads at pleasure ? What is easier, and what, 

 moreover, I will say, is oftener seen done, than for a bird to 

 stoop its head backwards or laterally, and rub it against the 

 feathers of other parts of its body ? in all probability for the 

 very purpose which Mr. Waterton says " he flatty denies" 

 without being able to assign any other use to the oil gland of 

 birds, or to advance one single opinion, grounded upon any 

 fact, against the received belief. This last argument is no 

 better than if one were to say that cats could not wash the 

 back parts of their heads because their paws, which they use 

 for that purpose, extend only in a forward direction ; or that 

 it were impossible for them to wash their faces at all, because 

 they use only their saliva for that purpose, which how are 

 they to get applied to the back part of their heads ? The 

 story of the eagle " varnished over," which next follows, I 

 will not comment upon any more than just to say that, if me 

 judice" Mr. Waterton has accounted for its appearing so 

 by an argument which militates against his own ,- for if the 

 difficulty be great for a bird to oil every part of his body 

 with oil obtained from the gland, on account of the impos- 

 sibility (which does not exist, as I have shown) of his getting 

 at the back of his head, I would ask, is not the difficulty in- 

 creased tenfold by supposing him to cover every part of his 

 body with slime by rolling on a fish? How is he (it might 

 just as well be asked) to besmear his head ? is he to stand 

 upon it, on the fish, or how ? I leave Mr. Waterton to an- 



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