Some Experiments of Luther Burbank 



year, a number of unusual sports in various local- 

 ities. This is probably a matter of season, the 

 forces outside bringing about parallel mutations. 

 The evolution of species is largely dependent on 

 crossing the variations contained within it. Forms 

 too closely bred soon run out, because generally 

 only by crossing does variation appear. It is of 

 great advantage to have the parents a certain dis- 

 tance apart in their hereditary tendencies. If too 

 close together there is not range enough of variety. 

 If too far apart, the developed forms are unfitted 

 for existence because too unstable. Correlate a 

 changes work together to produce the ej^ect of mutattQns, 

 Environment efFects a permanent change in species 

 by selection of those which fit it or by producing 

 changes in individuals which are better equipped 

 to survive. Heredity is the sum oj all past environ- 

 menty conditions both latent and apparent. Latent 

 traits often arise when circumstances make them 

 possible. Environment of a lifetime does not 

 necessarily or usually appear in another lifetime, 

 but continues in the same direction and will strike 



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