PRIMROSE ; THE ANATOMY OF THE ORANG OUTANG 
15 
obviously associated with the flexion or bending of the digits, the grooves 
existing opposite the joints at which the movement in question takes 
place. These grooves are converted into deep clefts when the fingers 
are fully bent. In the palm proper, similar markings on the skin are 
observed. Two very noticeable ones run almost parallel to one another 
from near the base of the index finger inwards towards the inner border 
of the palm. These grooves are about i cm. distant from each other 
They do not run transversely across the palm, but their course is very 
oblique, the inner extremity of each line being much nearer the wrist 
than the outer extremity. These markings are associated with the flexion 
of the fingers upon the palm, and are converted into deep fissures when 
the fingers are folded in upon the palm. Certain markings run in a more 
longitudinal direction. These begin near the wrist. One is clearly 
associated with the movements of the thumb towards the palm ; it 
curves forwards from the mid-point of the wrist, around the base of the 
ball of the thumb, to terminate on the outer border of the palm, some- 
times joining the nearer of the two oblique lines already described. 
This curved line is converted into a cleft when the thumb is opposed to 
the palm or to the other digits ; it is therefore clearly associated with 
the movement of opposition of the thumb to the palm or the other 
digits. Other longitudinal markings are associated with the adduction 
or abduction of the fingers. Occasionally the ball of the little finger is 
also marked off by a more or less distinct curved line. 
Now, if we compare the foregoing with the markings which are observ- 
able in the photograph of the palm of the hand of our Orang (see reproduc- 
tion of photograph) we find a corresponding series of markings. We 
notice, however, that the ball of the very rudimentary thumb in the Orang 
is not developed to anything like the proportions attained in man. The 
curved line at the base of the thenar eminence is present, but what is 
more marked is the cleft which indicates adduction of the thumb rather 
than opposition. Then one observes a very marked difference in the 
markings running across the palm. These are remarkable in being 
transverse rather than oblique in direction. We observe also certain 
less clearly marked longitudinal lines associated with adduction and 
abduction of the fingers. Let us now consider the significance of the 
difference in the markings in the human hand compared with those of 
the Orang. Professor Goodsir, of Edinburgh, long ago^ well indicated 
a distinctive difference between the hand of man and that of the ape 
when he stated that the hand of man could grasp a sphere whilst the 
hand of the ape could grasp a cylinder. 
“ Goodsir’s Anatomical Memoirs,” Edited by Prof. Wm. Turner, Edinburgh, 1868, Vol. I, p. 239. 
