THE RATE OF GROWTH IN THE HORSE 



293 



Hermit. From the twenty - 

 fourth week onwards the limbs 

 grow faster than the trunk. 

 In front the increase in growth 

 is mainly beyond the wrist- 

 joint, while in the hind-limb 

 it is chiefly beyond the knee- 

 joint or stifle. In both fore- and hind- 

 limbs the increase is greatest for some time 

 in the middle metacarpals (fig. 565, III) 

 and metatarsals — i.e. in the fore and hind 

 cannon bones. In the case of Hermit^ (the 

 1867 Derby winner), when the humerus is 

 taken as equal to 100, the third metacarpal 

 is equal to 76'1. In a seven-months fo3tus, 

 however, with the humerus equal to 100, 

 the third metacarpal may be over 90, while 

 at nine months it may be over 110, and 

 at birth 130 — i.e. relatively well-nigh twice 

 the length of the third metacarpal in Her- 

 mit. A similar rate of growth characterizes 

 the third metatarsal bone. This increase in 

 the cannon bones during the second half of 

 the period of gestation explains to a large 

 extent the great length of the foal's legs at 

 birth; it also accounts for the fact that the 

 cannon bones — the bones considered of so 

 immense importance in all kinds of horses 

 — increase but little in length after birth. 

 In the case of a thoroughbred, e.g., the 

 third metacarpal appears only to increase 

 3 cm. (barely 1;^ inch) after birth,^ while 

 the main bone of the fore-arm (the radius) 

 often increases 9 cm. (3|- inches), or nearly 

 throe times as much as the front cannon 

 bone. 



'The skeleton of Hermit is preserved in the Royal Veteri- 

 nary College Museum, Camden Town, London. Eclipse's skele- 

 ton is in the Royal College of Veterinary Surgeons Museum, 

 Red Lion Square, London. 



- Though the cannon bones may only increase 1 inch in length after Ijirth, they may increase 3 or even 

 4 inches in circumference in a 14-hands horse. 



Fetloclijoini 



Fig. 565. — Fore-limb (tweniy-three 

 weeks), natural size 



