THE RATE OF GROWTH IN THE HORSE 



289 



days. The growth is at the outset so deliberate that even at the end of 

 the fifth week the limb rudiments (fig. 560) are only 2 mm. (about ^ inch) 

 in length. After a time, however, the rate of growth is accelerated, with 

 the result that before the middle of gestation (the twenty-fourth week) is 

 reached they are relatively as large as in the full-grown horse. Having 

 reached this size, it might be assumed that they would continue to main- 

 tain the same proportions up to the time of birth. This assumption would, 

 however, be wide of the 

 mark, and in fact would 

 never be made by any- 

 one aware of the Q;reat 

 relative length of the 

 legs in the new-born 

 foal (fig. 561). To have 

 a chance of survivina; in 

 a wild state — of escap- 

 ing prowling wolves or 

 hungry hyjenas, jackals, 

 and hunting dogs — a 

 foal must almost from 

 the moment of its ap- 

 pearance on the scene 

 be capable of keeping 

 up witli the troop into 

 which it is so uncere- 

 moniously introduced — 

 sometimes apparently to 

 the annoyance of the 

 ever-watchful leader and 

 head of the family.^ To 

 succeed in this it re- 

 quires legs long enough 



to gallop at least as fast as the older members of the herd. It is doubtless 

 for this reason that during the second half of the period of gestation the 

 limbs grow very much faster than the trunk, with the result that for 

 some weeks before birth they are relatively not only extremely long, 

 but so wonderfully perfect in all their parts that, as in certain other wild 

 ungulates, a foal is no sooner ushered into the world than it is galloping 

 merrily along, carefully shadowed by its dam. 



^ Stallions in a wild state sometimes endeavour to compel mares to leave their foals ; thus all the more 

 ensuring that only vigorous offspring survive. 



Fig. 560. — Horse Embryo (five weeks) 



