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POPULAR SCIENCE MONTHLY 



lactea taken from the high Sierras where it is a dwarf, becomes, after 

 two years of cultivation, more than twice as high as the original stock, 

 but not nearly as high as the same species grown in the valley. 



" Crossing is done to secure a wealth of variation. By this means 

 we get the species into a state of perturbation or ' wabble,' and take 

 advantage of the l wabbling ' to guide the life forces into the desired 

 habits or channels. The first crossing is generally a step in the direc- 

 tion in which we are going, but repeated crossing is often necessary and 

 judicious selection always necessary to secure valuable practical results. 

 Crossing may give the best or the worst qualities of the parent, or any 

 other qualities; and previous crossings often affect the results." 



" Hybridization differs from 

 ordinary crossing only in degree. 

 A species is only a race which has 

 assumed greater fixity. The pur- 

 poses and results of crossing within 

 the species and of hybridization of 

 different species are essentially 

 alike. The formation of the new 

 individual by the sexual relation 

 of two parents is in itself a species 

 of crossing, giving each new indi- 

 vidual in its degree new traits or 

 new combinations." 



" Bees and other insects, as well 

 as the wind, cross plants, but they 

 do not work intelligently, therefore 

 rarely to any advantage econom- 

 ically to man. No mechanic could 

 invent such devices as those which 

 tend to prevent self-crossing in plants. .4// evolution and improve- 

 ment are dependent on crossing, therefore nature has produced more 

 wonderful devices for this purpose than for any other." 



"Mutations, or saltations, are often found; that is, fixed forms 

 springing up, generally from unknown causes, forms which are not 

 hybrids, and which remain constant; as, for instance, colored flowers 

 which yield white forms, these yielding white constantly in their 

 progeny. These mutations can be produced at will by any of the 

 various means which disturb the habits of the plant. It comes out 

 when the conditions are ripe. New conditions bring out latent traits. 

 I should expect mutations to arise in the American primrose and most 

 other plants under wholly new conditions. Extra food or growth force 

 as well as crossing favors variation, as does abrupt change of conditions 

 of any kind. Five or six generations will usually fix a mutation. 

 Sometimes it is fixed at once." 



Primus, the First Fixed Rtjbus Species 

 Artificially Produced. 



