CHAPTER III 



THE SURVIVAL OF THE FIT 



The plants that most perfectly meet their conditions are 

 able to persist. They perpetuate themselves. Their off- 

 spring are likely to inherit some of the attributes that 

 enabled them successfully to meet the battle of life. The 

 fit (those best adapted to their conditions) tend to survive. 



Adaptation to conditions depends on the fact of varia- 

 tion; that is, if plants were perfectly rigid or invariable 

 (all exactly alike) they could not meet new conditions. 

 Conditions are necessarily new for every organism. It is 

 impossible to picture a perfectly inflexible and stable succes- 

 sion of plants or animals. 



Breeding. — Man is able to modify plants and animals. 

 All our common domestic animals are very unhke their 

 original ancestors. So all our common and long-culti- 

 vated plants have varied 

 from their ancestors. Even 

 in some plants that have 

 been in cultivation less than 

 a century the change is 

 marked : compare the com- 

 mon black-cap raspberry 

 with its common wild ances- 

 tor, or the cultivated black- 

 berry with the wild form. 



By choosing seeds from a plant that pleases him, the 

 breeder may be able, under given conditions, to produce 



7 



Fig. s. — Desirable and Undesirable 

 Types of Coiton Plants. Vv'hy? 



