No. 637] FIRST GENERATION HYBRIDS i 21 



dominant characters appear represents roughly one half 

 of the germinal changes that are taking place, new reces- 

 sive characters originating at approximately the same 

 rate. The preponderance of recessive characters would 

 then be explained, as the result of their preservation in 

 a hybrid condition. 



MiNOE VaEIATIONS OcCUE with GrEEATEE FeEQUENCY THAN 

 MaJOE VaEIATIONS 



This assumption is made necessary by the fact that 

 the abnormalities which are sufficiently conspicuous to 

 be identified and isolated will account for a part only of 

 the reduction of vigor that follows inbreeding. A part 

 must be due to the combined effect of minor unfavorable 

 variations, the effect of individual variations being in- 

 sufficient to produce changes that can be distinguished 

 from environmental fluctuations. 



That minor variations are more numerous than major 

 is almost self-evident if large and small variations form 

 a continuous series, as they seem to do, since there is a 

 limit to the largeness of variations but none to their 

 smallness. If further proof is needed it follow^s from the 

 fact that most major variations can be resolved into less 

 comprehensive variations and these subsidiary or minor 

 variations must be more numerous than the major varia- 

 tions of which they form parts. 



As East has noted, our classification of variations into 

 large and small may have only a remote relation to the 

 importance of characters in the plant's economy. But 

 whether judged by the change in appearance or by their 

 importance to the organism, it is certain that larger or 

 more fundamental changes must occur less frequently 

 than smaller or less important variations. 



The Natuee of Vaeiations in Maize 

 The appearance of deleterious characters when maize 

 is inbred and their disappearance when crosses are made, 

 would follow whether the characters were the result of 

 recombination or of mutation. 



