THE RATE OF GROWTH IN THE HORSE 



297 



TABLE III. SHOWING RATE OF GROWTH IN A HORSE DURING THE FIRST THREE YEARS 



The length of the head gradually increases all through the first year, 

 when the maximum length is nearly attained. The increase is mainly 

 below the orbit, the space between the inner canthus of the eye and the 

 upper margin of the nostril being nearly doubled during the first two years. 



It will be noticed from Table III that the girth is all but doubled 

 during the first year. 



Why, it may be asked, is the growth in the horse arrested so much 

 sooner than in man? In the horse, as in man, the majority of the long 

 bones consist of a shaft and of two end-pieces (epiphyses) (fig. 566, shaft, 

 ep., ep.). The increase in the length of the typical long bones takes place 

 at the junction of the shaft with the epiphyses. This zone of growth is a 

 source of weakness, and the sooner the terminal pieces which by their 

 free ends enter into the joints firmly coalesce with the shaft the better. 

 In the horse this fusion takes place at a comparatively early stage, and 

 when it has been once effected all further increase in length becomes im- 

 possible. 



The question may now be asked : Can any practical use be made of all 

 this information as to the rate of growth in the horse? 



To this question an affirmative answer may very safely be given. In 

 England it is often taken for granted that the sire counts for infinitely 

 more than the dam. If the sire happens to be more impressive than the 



