338 
POPULAR SCIENCE REVIEW. 
in greater quantity wlierever resistance is most needed, as in 
tiie palm of tire hand and sole of the foot ; while the yellow 
fibres are a highly elastic tissue, owing to their minute fibriilae 
being arranged in interlacing curves, and these fibres cross each 
other repeatedly, and branch so as to form minute lozenge- 
shaped interstices, which are filled up principally by the white 
fibres. These yellow fibres, accordingly, as might be antici- 
pated, exist in greater abundance where elasticity is a special 
requirement, as at the flexures of the joints, the lips, etc. 
The uppermost surface of the cutis or true skin is strangely 
uneven and irregular, being elevated into a vast number of 
minute papillae, which are about l-100th of an inch in length, 
and 1 -250th of an inch in diameter. Minute as these little papillae 
are, each possesses a ramification of vascular capillaries and 
of nerve fibres ; the latter, though not traceable to the very 
surface — being* in fact the essential agents in the sense of 
touch, for that is the function of these papillae, — they are the 
seat of the tactile power, and accordingly we find them de- 
veloped in the greatest number and perfection where the 
tactile power is highest, as along the tips of the fingers and 
the lips in man, the lips specially in many quadrupeds, as the 
horse — these organs being the principal seats of the tactile 
power in them ; also along the membranous expansion of the 
wings in bats, where the sense of touch and appreciation of 
impact are so delicate that the animal, even though blinded, 
can fly between suspended threads without touching them. 
These papilke are also very well developed on the trunk of the 
elephant, the snout of the tapir, and at the roots of the hairs 
of the whiskers in the feline tribe, as well as on the under- 
surface of the prehensile tails of some of the monkey tribe, 
where the sense of touch is so delicate that they can ascertain 
by clasping it in their tails whether a nut has a sound kernel 
or not, and so save themselves a useless trouble and disappoint- 
ment in cracking it if unsound. These papillae are quite dis- 
tinguishable on looking at the hand, for their extremities are 
received into depressions on the under-surface of the scarf-skin, 
and when this is stripped off and examined with a low power 
these pits or depressions are well seen, arranged in single or 
double rows, which correspond with the papilke beneath, and 
above with the grooves or furrows which are visible on looking 
at the palm of the hand and inner surface of the fingers. These 
furrows are caused by the scarf-skin dipping in between the 
rows of papilke, and all along each furrow at very minute intervals 
may be seen little cross lines which indicate the separations 
of the individual papillae, or rather pairs of papillae, for 
they are usually arranged in pairs. . The number of these 
papillae is immense ; a square inch of the palm of the hand will 
