THE RATE OF GROWTH IN THE HORSE 



291 



563). Marked progress is made during the seventh week, with the result 

 that before the eighth week is reached the limbs have all the distinctive 

 equine characters and are about one-third of the total length of the embryo 

 the embryo measuring 3 cm., the limbs nearly 1 cm. Before the eighth 

 week is reached not only are the elbow and "knee" evident, but the fetlock 



Fig. 562. Hind Limbs and 

 Tail (four weeks) 



Fig. 563. Hind Limbs and Tail 

 (six weeks) 



Fig. 564. Hind Limbs and Tail (eight weeks) 



and frog of both fore- and hind-limbs are fairly well moulded, and in 

 the latter the true knee (stifle) and hock are well defined (fig. 564), the 

 distance from the hock to the tip of the developing hoof being 7 mm. 

 By the end of the eighth week we have a horse in miniature. At this 

 stage (the total length of the embryo being 6 '5 cm.) the distance from the 

 withers to the tip of the curved and pointed hoof is 3*3 cm., from the 

 elbow 1*9 cm., while the length from the hock is 1'3 cm. 



In figs. 562, 563, and 564 the growth of the hind-limbs and tail from 



