24 Mr. Rennie on the Cleanliness of Animals. 



wards, and which serve several important purposes, such as 

 lapping milk, and filing minute portions of meat from bones. 



Magnified view of a portion of the upper surface of the Cat's Tongue. 



But what falls chiefly to be noticed here, is its important use 

 in keeping the fur smooth and clean ; and cats are by no means 

 sparing in their labour to effect this. The female cat is still 

 more particular with her kittens than herself, and always em- 

 ploys a considerable portion of her time in licking their fur 

 smooth. The little things themselves, also, begin, when only 

 a few days old, to perform the office for themselves ; and I have 

 observed the half-fledged nestlings of the black cap (Sylvia 

 atricapilla), and a few other birds, preening their feathers as 

 dexterously almost as their dam herself could have done. 



It requires the employment of a microscope of considerable 

 power, to observe the very beautiful structure of the foot of 

 the two-winged flies (Muscidce), which still more closely re- 

 sembles a currycomb, than the tongue of the cat does. This 

 structure was first minutely investigated by Sir Everard Home 

 'and Mr. Bauer, in order to explain how these insects can walk 

 upon a perpendicular glass, and can even support themselves 

 against gravity. Of the structure of the foot of flies, con- 

 sidered as an instrument for cleaning, I have not hitherto met 

 with any description in books of natural history, though most 

 people may have remarked flies to be ever and anon brushing 

 their feet upon one another, to rub off the dust, and equally 

 assiduous in cleaning their eyes, head, and corslet with their fore- 

 legs, while they brush their wings with their hind legs. In the 

 common blow-fly (Musca carnaria), there are two rounded 

 combs, the inner surface of which is covered with down, to serve 

 the double purpose of a fine brush, and to assist in forming a 

 vacuum when the creature walks on a glass, or on the ceiling of 

 a room. In some species of another family (^mlidce), there are 



