HAND AND FOOT PRINTS 
Corrugated Skin of Palm and Sole Furnishes Many Interesting Problems—Limits 
of Heredity in Finger-Print Patterns—The Friction-Skin 
Patterns of Monkeys and Apes 
INGER-PRINTS are naturally 
FH associated in one’s mind with 
criminals; but the possession of a 
complicated pattern on the ‘“‘fric- 
tion-skin”’ of the hands and feet is by no 
means confined to the ladies and 
gentlemen of the Rogues’ Gallery. Not 
only do all human beings possess such 
friction-skin, but the anthropoid apes 
have quite similar patterns, which can 
be followed down to their rudiments in 
the lower monkeys, and traced in many 
other animals. 
Certainly those geneticists who an- 
nounce the futility of looking for a 
‘“purpose’’ in anything save themselves 
a lot of trouble; for a long debate has 
been carried on over the possible 
use of these palm and sole patterns. 
Galton tells! a good story of Herbert 
Spencer in this connection. 
“An amusing instance of his strong 
leaning to a priort reasoning rather 
than to experiment occurred on _ his 
coming to a laboratory I had then 
established for anthropological purposes. 
I told Spencer of the difficulty of 
accounting for the peculiarities in the 
pattern of finger-prints, and that the 
dissection of embryos had thus far told 
no more than that they could be referred 
to folds of membrane in which the 
sudorific glands were formed, but threw 
no light on the reason why the pattern 
should here be a whorl and there a loop 
and soon. He said that dissection was 
not the best way to find out what I 
wanted to know; I ought to have 
started from a consideration of the use 
of the ridges, and he proceeded to 
elaborate a line of argument with great 
fulness in his usual sententious way. It 
was to the effect that the mouths of the 
ducts, being delicate and liable to 
became Mrs. Harris H. Wilder. 
injury from abrasion, required the shield 
of ridges, and on this basis he reared a 
wonderfully ingenious and complicated 
superstructure of imaginary results to 
which I listened with infinite inward 
amusement. When he had quite con- 
cluded, I replied with much humility, 
that his arguments were most beautiful 
and cogent and fully deserved to be 
true, but unfortunately the ducts did not 
open out in the shielded valleys, but 
along the exposed crests of the ridges. 
He burst out with a good-humored 
laugh, and then told me the story, which 
also appears in his Autobiography, 
of Huxley’s saying that if Spencer ever 
wrote a tragedy, the plot would be the 
slaying of a beautiful induction by an 
ugly fact.” 
ORIGIN OF THE RIDGES 
Later students, while proceeding from 
sounder premises than Spencer, have 
been equally obliged to depend on 
speculation. Miss Whipple, who 
studied the genesis of the ridges which 
characterize friction-skin in various 
orders of mammals, showed? that “‘they 
are formed from either (1) the coales- 
cence of separate epidermic units, each 
with a sweat. gland (and typically, a 
sebaceous gland and a hair) which 
arrange themselves in rows and form 
single ridges; or in other cases from (2) 
epidermic rings, formed by a coalescence 
of the primary units in circles, which, 
by becoming elliptical and arranging 
themselves in rows corresponding to 
their longitudinal axes, form simul- 
taneously two rows of ridges.” 
It is now affirmed that the sweat 
glands open on the crests of the ridges 
in order that their openings may not 
be clogged up. As to the function of 
‘In Duncan’s biography of Spencer (New York, 1908), Vol. ii, pp. 263-264. 
? Zeitschrift f. Morpholcgie u. Anthrcpolcgie, Pand vii, pp. 261-368. 
Miss Whipple later 
511 
