Artificial Selection. — Darwin was much impressed 

 with the results of artificial selection or selective breeding 

 that man has effected among domesticated animas and 

 cultivated plants. There is evidence that the nearly 200 

 well-marked breeds of domestic pigeons have all descended 

 from the blue rock-pigeon [Colutnbia liviay, and the 

 various breeds of poultry from the Indian jungle fowl 

 (Gallus- bankivus). The various breeds of horses, rabbits 

 and ducks too have each probably come from a single wild 

 species. On the other hand the breeds of dogs and cattle 

 have arisen from more than one species. ^ (See page 33). 



The origin of most of our garden flowers, fruits and 

 vegetables is lost in obscurity, but many new forms are 

 being evolved before our very eyes. 



Darwin reasoned that if man has been the agent in 

 evolving all these forms in a relatively short time, Nature is 

 capable of effecting much also in a very long time. 



Kinds of Evolution.— Evolxiiion has taken place in 

 many directions. There has been convergence as well as 

 divergence in development, just as .there has been regressive 

 development as well as progressive development. Diver- 

 gent progressive evolution is the type usually considered 

 and represented in our genealogical trees. Examples of 

 convergent development are the swift and the swallow, 

 which are birds very distantly related; the bird and the bat, 

 etc. (Read Willey's Convergence in Evolution). 



Other cases where analogies are developed are Ty- 

 phlops, a burrowing snake, Amphisbaena, a burrowing 

 lizard, Siphonops, a burrowing amphibian, which are 

 more or less worm-like; Pteromys, a flying squirrel, and 

 Petaurus, a flying phalanger; the porcupine (Erethizon), a 

 rodent, the hedge-hog (Erinaceus), an insectivore, and the 

 spiny ant-eater (Echidna) a monotreme, all spine covered 

 animals; also the eyes of Molluscs, vertebrates and 

 Polychaete worms. 



Correlation in Evolution. — "A variacion important in the 

 present may bring in its train one that is designed to be im- 

 portant in the future, and a variation too small in itself to 

 be of value may be carried over the dead point into effect- 



(1)— Some of the common breeds of domestic pigeons are the tumbler, 

 pouter, fan-tail, carrier, homing, barb, trumpeter, common mon- 

 grel, archangel, fairy swallow, blackwinged swallow and bluetts. 



(2) — The student of organic evolution should read and re-read Dar- 

 win's Origin of Species and Variation of Animals and Plants 

 under Domestication. The latter is not as well known as the 

 former, but in most respects it is equally important. 



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