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AFRICAN GNAWERS 261 
but few which are furnished with so singular a structure as the well- 
known porcupine, whose wonderful array of spear-like quills has earned 
for it world-wide renown. But for this prickly coat the porcupine 
would have no chance of beating off its foes, for it is neither a strong 
nor a swift animal, and so would be unable either to fight with or to 
escape from an antagonist larger than itself. 
There is one very great mistake, however, which people often 
make with regard to this curious spiny covering, and that is to sup¬ 
pose that the porcupine can use its quills in the manner of spears, 
and hurl them at any foe who is foolish enough to come within dis¬ 
tance. This power, however, the animal does not possess. All that 
it can do when attacked is to spread its quills and run backwards 
towards its foe, for it is quite unable even to loosen its spines in their 
sockets, much less to hurl them through the air and so strike its 
enemy at a distance. It is true enough that animals are sometimes 
found with one or more quills piercing their bodies, but these are such 
as have attacked a porcupine and have borne away with them 
evident signs of the encounter. For the quills of the porcupine are 
set quite loosely in the skin, and are furnished with saw-like edges, so 
that, when they enter the flesh of an animal, they not only remain in 
the wounds, but constantly penetrate deeper and deeper. Even so 
powerful an animal as the tiger has been found to have his head and 
paws filled with the spines of a porcupine, which he had attacked, but 
had failed to conquer. 
These terrible spines are nothing more nor less than hair. If 
one is split up very carefully, it is found that it is formed of a number 
of hair-like threads pressed very closely together, and these threads if 
placed under a microscope, would be found to possess just the same 
structure as real hair. The same is the case with the horn of the 
rhinoceros, which, very different though it appears ; is really formed of 
nothing more than hair. 
