508 THE HORSE'S POSITION IN THE ANIMAL WORLD 



pads in man are really hardened cuticle, excessively thick portions of the 

 cuticle in fact. 



In the foot of the dog, however, both on the surface and in section, 

 the structure differs from the thickened cuticle of man's hand and foot, and 

 also from true horn. Indeed, the minute anatomy of the organ exhibits a 

 most perfect type of the transition or change from cuticle to horn. (See 

 Plate LXIX.) 



In the case of the dog the plantar and palmar pads are in perfect form 

 and active function. In man, however, they are more or less accidental or 

 rudimentary. The palmar pads, or those on the palm of the hand, depend 

 for their development on the amount of manual work done, and they vanish 

 when that work ceases, while the growth of the plantar pads is checked by 

 the devices of civilization, including shoes and stockings, and the use of 

 various modes of locomotion in place of the natural acts of running and 

 walking. 



o 



FALSE NOSTRILS AND GUTTURAL POUCHES 



Two peculiarities in the anatomy of the horse yet remain to be 

 considered. The False Nostrils, as they are called, and the Guttural 

 Pouches. 



It is generally known to horsemen that the horse breathes solely 

 through the nostrils, owing to the great depth of the soft palate, which 

 entirely cuts off the cavity of the mouth from the opening into the breath- 

 ing tubes. In compensation the nostrils are flexible, and the opening on 

 each side is large enough to admit all the air which the animal rec[uires for 

 breathing under all conditions, which include violent exertion and a high 

 rate of speed. A curious pouch, 3 or 4 inches deep, cone shaped, having 

 its apex pointing upwards, and known as the false nostril, exists at the 

 entrance to the nasal chambers on each side. No use can be found for this 

 cavity. The tapir has the same structure in a more highly developed form, 

 and it also exists in the rhinoceros. 



To discover the real significance of this peculiar sac is now impossible; 

 most probably it was an important organ in some of the earlier hoofed 

 mammals, but unhappily the conservative earth only preserves in a fossil 

 state the bones and like resistant structures. All that might be learned 

 from even badly-kept soft parts has been lost to us, but the organ as we 

 now find it in the three animals named is valuable as connecting the 

 creatures of to-day with those of other times. 



Guttural pouches (Vol. I, p. 505) are cavities at the back of the mouth, 

 also communicating with the air-passages, and with a canal which enters 



