150 THE HAIR AND FUR OF ANIMALS. 



retiring backwards, as it always does upon sus- 

 picion of peril, not turning round, which the size 

 of its runs does not permit, but tail foremost, until 

 it arrives at some collateral gallery, when its flight 

 is head foremost, as with other creatures. If this 

 fur had been strong, as in the rat, or mouse, in 

 these retreats 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 preventing, 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 

 believe in the beneficence of the All-wise Creator, 

 we must conclude that such peculiar fabrications 

 were resorted to for the purpose of being imme- 

 diately 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 ren- 

 dered manifest by the microscope ; but three or 

 four may be mentioned. The fur or clothing of the 

 mole, (Plate 3, Fig. 4,) A, is internally composed of 

 collateral bars. In man the hairs have at times a 

 central tube, for the conveyance of medullary mat- 

 ter, as in bones, or some nutriment analogous to it ; 

 but in the mole there appears to be no communi- 



