88 SCIENCE FROM AN EASY CHAIR 



and African asses and the zebras) is found in the curious 

 wart-like knobs 1 on the legs, which are called "chest- 

 nuts." These warty knobs appear to be the remains in 

 a "dried up" condition of glands, such as are found in 

 the legs of deer in a similar position, and secrete a glairy 

 fluid. In new-born colts they sometimes exude a fluid, 

 and also more rarely in adult horses. The fluid attracts 

 other horses (probably by its smell), and also causes dogs 

 to keep quiet. The horse has one of these wart-like 

 " chestnuts " above the wrist 

 joint (so-called knee) on the 

 inner side of the fore-leg. And 

 so have all the asses and 

 zebras. But the horse (Fig. 1 2) 

 has also a similar "chestnut" 

 HORSE ASS on t ' ie i nner s * de f eacn f 



FIG. i2.-Fore and hind legs of its hind-legs, below the heel- 

 horse and ass, to show the bone, or " hock." This hind- 

 " chestnuts," and the absence J e g chestnut is absent in all 



&!!**"* *^* asses and zebras< This differ ~ 



ence between the horse and 



ass can be tested by my readers on any roadside by 

 their own observation. The hind-leg chestnut is also 

 absent in certain breeds of ponies from Iceland and the 

 Hebrides. Its presence and absence are interesting in 

 connection with the disappearance of the face-gland or 

 pre-orbital gland in all recent horses, asses, and zebras. 



The " chestnuts " of the horse have sometimes been 

 compared erroneously to the " pads " on the feet of other 

 animals, and supposed to be survivals of a" pad " in 



1 The names " malander " and " salander " have been recently 

 applied by zoological writers, apparently by misconception, to these 

 "callosities" or "chestnuts." Those names are used by veterinary 

 surgeons to describe a diseased condition of this part of the horse's 

 leg (Italian "mal andare n \ and do not apply to the "chestnut" 

 itself, which is sometimes called "castor." 



