CHAPTER VIII 

 REPRODUCTION 



Even the earliest observers of nature, crude though their ideas of 

 hfe were, can hardly have escaped the knowledge that new individuals 

 are brought into existence by other individuals of the same kind. Ani- 

 mals have been domesticated from time immemorial, and the method of 

 producing new individuals among such animals must have been well 

 known. Nevertheless early writings reveal a common belief that many 

 animals even among the higher groups arose occasionally in some other 

 manner. Moreover, there was a host 

 of animals of simpler structure and un- 

 known habits which were supposed reg- 

 ularly to come into existence without 

 the intervention of other living beings. 

 This conception of the origin of in- 

 dividuals is comprised under the term 

 abiogenesis or spontaneous generation. 



Spontaneous Generation . — For 

 centuries before the invention of the 

 microscope it was commonly believed 

 that living things arose spontaneously 

 from non-living material ot- that more 

 complex animals might arise in very 

 short time from simple animals or from 

 the dead bodies of animals or plants. 

 The ancient Greeks believed that 

 animals arose from mud at the bottom ,_!^'^\^^2^"~^'"^"^^'^? ^l^'' ^^'^^'~ 



1694. (From Garrison s History of 

 of bodies of water. Similar ideas have Medicine, W. B. Saunders Co.) 



been current among the people of many 



nations. Directions may be found in certain old books for the artificial 

 generation of bees, and even of mice. During the middle ages strange 

 ideas were held as to the transmutation of animate objects into complex 

 animals. The barnacle Lepas anatifera was then considered to be the 

 fruit or leaf of a tree, probably because it was found attached to the 

 branches of floating trees or driftwood thrown upon the beach by storms. 

 From these barnacles in turn geese were supposed to originate. 



Many erroneous ideas thus arose and were accepted largely because 

 they were proposed by men of some authority, and in part because there 



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