18 Animal Life 
for instance, to indicate that the 
movements of a giraffe or a camel 
are very different from those of 
a horse. This is probably due 
to the fact that a very imperfect 
recognition of the nature of the 
ordinary movements of locomotion 
(including those of man himself) 
exists among most of us. Under 
these circumstances it has been 
thought that a brief and simple 
explanation of some of the leading 
types of such movements in land 
animals, and more especially mam- 
Fig. 3. ig. 4. mals, would be acceptable to many 
of the readers of ANIMAL LiFe. 
It should be premised that, in addition to the differences due to whether animals 
are bipedal or quadrupedal, many of the peculiarities or disabilities in the movements 
of particular species depend upon the relative straightness or otherwise of their lmbs. 
That is to say, the extent to which one segment of the limb is flexed upon the other, and 
the consequent difference in the size of the angles formed by the junction of such segments. 
The relative lengths of the fore and hind limbs also exercise an important influence on the 
movements of their owners; those animals which have the longest and most flexed limbs 
being, prund facie, the swiftest runners and the longest and highest leapers. 
The great majority of land quadrupeds move thew limbs, when walking or running, 
in a diagonal order, so that their tracks form a series of ellipses placed end to end, the 
track of one complete movement forming a figure of eight. Man, in spite of his gait 
being bipedal, is really no exception to this rule, for in walking or running (Figs. 2 and 3) 
he swings his arms as well as moves his legs, and the left arm is swung when the 
right leg is advanced, and wice versa. In other words, the synchronous movements of 
the limbs are diagonal; and the combined tracks of the hands in the air and of the 
feet on the ground would form the above-mentioned ellipses, or figures of eight. The 
part which the arms play in locomotion is perhaps better shown in skating; in 
running it is generally found preferable 
to bend the arms on the chest and 
dispense altogether with them swinging 
movement, the upper part of the body 
being at the same time inclined forwards. 
The alternating diagonal movements of 
our two pairs of limbs in walking are 
probably retained to a great extent as 
an aid in maintaining the balance; but, 
in any case, they may be regarded as an Vg 
inheritance from our four-footed ancestors. al 
Owing to the straightness of his legs, man 
is a comparatively poor jumper, although 
he acquires additional power by flexing 
his limbs (Fig. 4), and thus diminishing 
the size of the angles formed by the 
inclination of their component segments 
at the moment of taking the leap. 
