‘FINGER-PRINTS—THEIR EVOLUTION AND SIGNIFICANCE. 209 
swinging from one cylindrical branch to another. In man’s 
hand the integumentary grooves are for the most part 
obliquely transverse, since the closure of his hand in the act 
of grasping is associated with a much more powerful and 
freely movable thumb, whereby it is possible for the hand 
to close upon and almost to envelop a spherical object. 
Now, wherever papillary ridges occur, except in the 
pattern areas, they follow, in their main lines of development, 
those transverse or obliquely transverse integumentary 
grooves which express the degree and nature of the grasping 
power of the hand and foot. 
My contention therefore is, that papillary ridges are speci- 
ally developed aids to the power of prehension, whether it be 
such as is required by the ape in his rapid and safe progress 
from branch to branch, or, as in the case of man, for the 
effective and secure handling of a weapon or a tool. If we 
compare the foot of a cat with that of a dog, we see that 
each possesses a set of well-developed “ pads,” but yet only 
the cat can climb freely in virtue of its sharp and effective 
hook-like claws. So it is in the case of many other climbing 
animals, They do not really grasp the object upon which 
they climb in the true sense of the term; nevertheless, the 
skin covering their pads is not devoid of papille although 
they do not form ridges, nor are the papille devoid of 
tactile sensibility. 
In the hands and feet of apes and men, grasping is not 
assisted by claws, but is performed by the disposition of the 
hand or foot with its digits upon the object laid hold of, 
the security of the grasp being augmented by the general 
development and arrangement of the papillary ridges, whose 
direction, except in the “ pad” areas, in the main corresponds 
to the foldings produced by muscular action. 
By applying oil or water to the skin of the palm or sole, 
Wwe may give it the equivalent of a perfectly smooth surface, 
but no condition less fitted for secure grasping could be 
imagined, notwithstanding the fact that sensibility to touch 
is not similarly impaired. 
A certain amount of moisture is certainly advantageous to 
effective grasping; and the palms and soles of apes are 
always exquisitely soft and velvety, for they avoid all risk of 
