Hybridization 



123 



the instability of hybrid offspring when propagated by 

 seed is notorious. We shall see the reasons for this later 

 when discussing mendelism. Wallace writes that "the 

 effect of occasional crosses often results in a great amount 

 of variability, but it also leads to instability of character, 

 and is therefore very little employed in the production of 

 fixed and well-marked races." We may remark again that, 

 because of the unequal and unknown powers of the parents, 

 we can never predict what characters will appear in the 



FIG. 34. Variation in hybrid pineapples. 



hybrids, although we are now beginning to understand 

 the reasons and to have rather definite expectations as 

 to probabilities. This fact is well expressed by Lindley a 

 half century ago, in the phrase, "Hybridizing is a game 

 of chance played between man and plants." 



Characteristics of crosses. Bearing these fundamental 

 propositions in mind, let us pursue the subject somewhat 

 in detail. We shall find that the characters of hybrids, 

 as compared with the characters of simple crosses between 

 stocks of the same variety, are ambiguous, negative, and 



