294 



BREEDING 



From the twenty-fourth to tlie beginning of the thirty-fourth week, 

 horse embryos often increase at the withers from 32 "5 cm. to 54 cm., while 

 from the elbow onwards the increase is from 21 cm. to 34'5 cm., and from 

 the point of the hock to the tip of the hoof the increase is 10 '5 cm. — i.e. 

 from 15 cm. to 2 5 '5 cm. 



At the fortieth week the embryo is about 86 cm. in length, the height 



I Radius 



at the withers being 76 cm.; from the 



jlh 



[Line ot r"""' 



(end pi":') 



VIns 



Carpsh I 

 (Wrist 'ionefl 



t'P 



y 



Wrist 

 ■ ("Knee) 



IV Metacarpa 



Metacarp 



al 



twestigej 



■) IV Digit 



II Dig 



t. (vestigej 



tpl 



elbow to the point of the hoof the dis- 

 tance is 52-53 cm., and from the hock 

 40-42 cm. 



Of the 22 cm. of increase in height 

 from the thirty-fourth to the beginning of 

 the fortieth week, 19 cm. is due to the 

 lengthening of the leg from the elbow 

 downwards; but during the last eight 

 weeks (i.e. 40-48) of foetal life there is 

 only an increase of about 9 cm. from the 

 elbow to the ground, while the total in- 

 crease at the withers is over 20 cm. 



At birth the foal of 14-hands parents 

 may be expected to measure 92 cm. at the 

 withers, 62 cm. from the point of the 

 elbow, and 45 cm. from the point of the 

 hock to the ground, the circumference be- 

 low the knee being 10 cm. 



From these figures it appears that dur- 

 ing development the actual increase in the 

 length of the limbs is greatest between the 

 twenty-fourth and fortieth weeks. The rate 

 of growth at the withers and from the 

 elbow and hock downwards during develop- 

 ment is graphically represented in Table I. Further enquiries may .show 

 that during the last eight weeks of foetal life there is a rapid formation 

 of bone, a hardening of tendons and ligaments, and a strengthening of 

 the muscles, so that immediately after liirth the foal may, even in times 

 of stress, keep its place in the herd. 



Having indicated the periods at which the unborn foal grows most 

 rapidly, I shall now deal with the rate of growth after birth. My ol)ser- 

 vations show that the rate of growth of the foal is decidedly unequal even 

 during the first three months. It might have been assumed either that the 

 increase would be continuous and equal during the first two or three years, 



III Met^carr^i 

 fethckjBint 



[Phalsngen 



Fig. 566.— Fore-limb (twenty-three weeks), 

 front view, natural size 



