ANIMAL LOCOMOTION. 67 



the ground is in both gaits the same. The front and hind feet of 

 heterochiral pairs impress the ground at the same places. The 

 intervals between the sets of heterochiral impressions are in the 

 walk about thirty-eight inches ; in a small horse they may be 

 twenty-five inches. The contrasts between the figures in the 

 photographs of the horse at the walk and at the trot are very 

 pronounced in the profiles. (See series 584 and 601.) But in the 

 foreshorten ings the two gaits present appearances which are very 

 similar. The reader may compare Figs. 4 to 8 with profit. 



The trot and the walk are both heterochiral, and vary in the 

 manner of lateral or diagonal positions of limbs. 



The chief difiPerence between the impressions made on yielding 

 ground of the feet in the trot and the walk is seen in the relative 

 distance between them. The impressions are much farther apart 

 in the trot than in the walk. 



Gaits are more variable in the slow than in the fast varieties. 

 This is inevitable, since the fast gaits depend upon uniformity. Dr. 

 Cryer, in conversation with the writer, states this as an impression. 



The Laterals in the Walk and the Rack contrasted. 



The lateral position as seen in the walk is essentially different 

 from that seen in the rack. In the walk the fore foot is in for- 

 ward strain, while the hind limb is in backward strain. In the 

 rack, the fore foot being in forward strain, the hind foot is in the 

 same position, so that the limbs are parallel to each other. 



In Procyon (series 744), the diagonal heterochiry shows that the 

 fore and the hind leg, say of the right side, are both in forward 

 movement, while the fore and the hind leg of the left side are in 

 backward movement. 



In lateral heterochiry the disposition is reversed : when the 

 fore limb is in forward movement the hind limb of the same side 

 is in backward movement. 



The graphic method of analysis embraces the following consid- 

 eration: The essential lines in a given movement have been drawn 

 and arranged in the same order as in the photographs. (See series 

 577.) As the walk is the most complicated of the gaits, it has 

 been selected as an example of this method. The advantage is 

 evident, for the observer is relieved of the action of but one pair 



