TELEGONY AND REVERSION. 149 



recent times that long hairs have extended up to near the 

 root. It is known to many that in most horses the hairs 

 from the upper two or three inches of the tail are shed 

 with the winter coat. But the shedding in the vast 

 majority of cases is so gradual, and the growth of the new 

 hair so rapid, that the loss of the dead hairs is hardly per- 

 ceptible. In the mule, on the other hand, the long hairs 

 from about six inches of the root of the tail are usually 

 shed so rapidly that only a covering of comparatively short 

 hair is left. My zebrules agree with ordinary mules in 

 this respect, but the shedding of the long hairs may be 

 more extensive, only the long hairs springing from the 

 lower third of the dock persisting. In Hyla, the Forest 

 pony's 1897 foal, all the long hairs of the upper 2| inches 

 of the tail were shed during April and May (1898), leaving 

 the base of the dock almost bare. In the sire and dam of 

 Hyla the hairs are shed very gradually from the root of 

 the tail — a casual observer would never notice that the old 

 hairs are being slowly replaced by new. The other fact is 

 that the wart (chestnut) is absent from the left hind leg. 

 Warts have never, as far as I am aware, been found on 

 the hind legs of asses or zebras, and they are generally 

 believed to be invariably absent from the hind legs of 

 mules. But they are also said to be sometimes absent 

 from the hind legs of horses. In the Forest mule (Fig. 42, 

 Hyla's half-sister) warts, as it happens, are present ; or, to 

 be more accurate, there are small, smooth, bare spots in the 

 position of warts. In all probability many mules have 

 vestiges of warts, and it is just possible that in horses said 

 to be without warts there may be similar vestiges. In one 

 of my zebrules there is a small wart on one of the hind 

 legs. The absence in Hyla of a wart from one of the hind 

 legs, the falling out of the hair from the root of the tail, 

 and the presence of faint indications of stripes across the 

 croup, may be looked upon as mere accidental coincidences, 

 or as the result of simple reversion ; but, on the other hand, 

 these unusual conditions may be due to "infection" — to, 

 let us say, some of the germ-plasm of the previous sire 



