GENERAL PRINCIPLES OF BREEDING, 15 



produced the varieties which are now so appar- 

 ent, is generally admitted. Very much of this 

 divergence is due to climatic influences, which 

 alone are sufficiently powerful, iu the changes 

 of food and of habit which necessarily follow, 

 to account for nearly all the varieties which 

 have been produced. A warm climate and a 

 bountiful supply of nutritious food from birth 

 to maturity promotes growth and development, 

 while a scanty supply of nutrition and a rigor- 

 ous climate have a positive tendency in the 

 opposite direction. A knowledge of the effect 

 of heat and cold upon growth and development 

 has been taken advantage of by breeders for the 

 purpose of producing dwarf specimens. The 

 breeder, of Bantam fowls is careful to have his 

 chicks hatched late in the season, so that the 

 early approach of cold weather may arrest de- 

 velopment. The bleak, barren and tempestu- 

 ous islands (lying in the high latitude of 59 and 

 60 deg.) north of Scotland, with their scanty 

 subsistence and long winters, have dwarfed the 

 horse of that country until he appears as the 

 diminutive Shetland pony, while, from proba- 

 ably the same original, the rich herbage, nutri- 

 tious grains and mild climate 10 deg. further 

 south, on the European coast, have given us 

 the immense draft horses of ancient Normandy 

 and Flanders. 

 But while climate andi the necessarily accom- 



