THE HAIR AND FUR OF ANIMALS. 107 



had been strong, 'as in the rat, or mouse, in these re- 

 treats for life it would have doubly retarded the progress 

 of the creature ; first by its resistance, and then acting 

 as a brush, so as to choke up the galleries, by removing 

 the loose earth from the sides and ceilings of the arched 

 Ways ; thus impeding at least, if not absolutely prevent- 

 ing, retreat; but the softness of the fur obviates both 

 these fatal effects. 



The construction of the hair and fur of different 

 creatures is very various and beautiful; and if we be- 

 lieve in the beneficence of the All-wise Creator, we 

 must conclude that such peculiar fabrications were re- 

 sorted to for the purpose of being immediately useful, 

 or as necessary to the condition of the animal. In a 

 mere sketch like this, it would conduct me infinitely 

 beyond my intentions, to enumerate the many varieties 

 of hair that are rendered manifest by the microscope ; 

 but three or four may be mentioned. The fur or clothing 

 of the mole is internally composed of collateral bars. 

 In man the hairs have at times a central tube, for the 

 conveyance of medullary matter, as in bones, or some 

 nutriment analogous to it ; but in the mole there appears 

 to be no communication with the body of the animal, 

 unless the perspirable matter is conducted alternately 

 from side to side along the bars. The fur of the bat 

 has knots like the rudiments of branches. The hairs of 

 the hamster mouse have a central perforation, appa- 

 rently uninterrupted throughout their whole length* 

 Some of the caterpillars (callimorpha caja) have spines 

 proceeding from the hair that invests their bodies,* 

 All these, and thje other various contrivances so manifest 

 in the coverings of animals, are probably designed to con- 

 vey off the perspirable fluids conducive to health in an 



* The organ, which inflicts the pain, or sting, when we incautiously 

 handle the nettle, is well known to be connected with a little vessel 

 containing an acrid fluid, which being compressed, rushes up the tube 

 of the organ, and is thus conveyed into the wound ; and it is rather 

 singular, that the larvae of the admirable butterfly, which feeds upon 

 the large hedge nettle, has the spines which arise from its body 

 branched, and each collateral hair arises from a little bulb, similar a- 

 that of the plant on which it is chiefly found. 



