ioo SCIENCE PRIMERS. [xxv. 



appear in the future plant ; whence it follows that the 

 progeny of any individual plant which has been fer- 

 tilized by another individual must differ more or less 

 from that which bore it. Also seeds taken from dif- 

 ferent parts of the same plant being differently nourished 

 will produce plants showing different amounts of un- 

 likeness to the parent ; and these sources of unlikeness 

 are further affected by the conditions under which the 

 seeds germinate and the future plant grows. 



151. Profiting by these facts, gardeners highly manure 

 certain plants, and cross-fertilize others, in order to 

 obtain new strains, as they are called ; and by raising 

 plants from all the seeds that ripen under these con- 

 ditions they obtain a large choice of individuals 

 differing in various degrees from their parents. 



152. Nature proceeds more slowly: very few indeed 

 of the seeds shed in a state of nature produce plants 

 that arrive at maturity ; most perish from falling on 

 stony ground ; or from drought ; or are eaten by 

 beasts, birds, or insects ; or if they grow, the young 

 plants are choked or eaten, or otherwise killed. Of 

 those that survive, such as have their parents' con- 

 stitutions are the most numerous, and such will 

 most resemble their parents in outward character. 

 Hence marked variations, though so easily produced 

 in a garden, are comparatively rare in a state of 

 nature. 



153. Origin of Species, There are two opinions 

 accepted as accounting for this ; one, that of inde- 

 pendent creation, that species were created under 

 their present form, singly or in pairs or in numbers : 

 the other, that of evolution, that all are the de- 

 scendants of one or a few originally created simpler 



