THE LIMIT OF SIZE IN MODERN ANIMALS 187 



by necessity on the absorbing effort to satisfy the 

 hourly cravings of hunger. It is doubtful whether 

 there is an average difference of half a hand in the 

 height of the four or five score of ponies admitted 

 to the annual show held at Lyndhurst by the 

 Association for the Improvement of New Forest 

 Ponies. Though many of these are dragged in, 

 rough and unkempt as a mop, and shaggy as a 

 poodle, unbroken, and almost unhaltered previously, 

 and bred by promiscuous intercourse in the wildest 

 parts of the forest, Nature levels up as it levels 

 down, and the two forces tend to produce a 

 uniformity in size which may be due to outside, 

 rather than to inside, forces. The case of the 

 horse is the more interesting, because its ancestral 

 types were, unlike those of most modern creatures, 

 smaller than the existing species. Its earliest known 

 ancestor was no larger than a fox. These were 

 succeeded by others of the size of sheep, and in 

 Pliocene times by creatures the size of donkeys. 

 Modern breeding, it must be remembered, has not 

 been directed solely to increase in size. Yet the 

 average of the thoroughbred has gained three inches 

 since the introduction of the Arabian horse. Size 

 is restricted by convenience and economic considera- 

 tions ; and the tendency at present is rather to 

 diminish than increase the bulk of the most useful 



