PROBLEM OF HIGHER FECUNDITY 109 



that "high fecundity is not inherited by daughters from 

 their dams." 



The Oregon experiments which have shown a remarkable 

 increase in production, with strong evidence that it was 

 due to selective breeding, do not appear to show that it 

 came in a sex-limited way. They show, on, the average, 

 that both sire and dam exert an influence, but that the in- 

 fluence is not confined to the immediate parents. It is true 

 that some males, as well as females, have a greater pre- 

 potency or power of transmitting fecundity than others, 

 but it cannot be said, so far as these experiments have gone, 

 that it comes only from "one side of the house." Table 

 on p. 102 may be studied in this connection. 



Progression and Regression. The production of the 

 progeny never reaches that of the parent stock when the egg 

 production of the parents exceeds the average of their 

 generation. There is, however, a progressive increase each 

 year when the parents have been selected among the indi- 

 viduals that have production records higher than the 

 average of the flock. (See table p. Ill Oregon Station ex- 

 periments.) This is the principle or law of progression. 



There is another principle or law operating in the other 

 direction ; that is regression. There will be regression or a 

 decrease in production unless the breeding stock be selected 

 among the highest producers. When no selection of any 

 kind is practiced, the tendency is downward. The average 

 of all the ancestry is pulling backward. Selection is neces- 

 sary if the breeder is to do no more than maintain the 

 standard of production. He cannot "rest upon his 

 laurels" without going backward. He must select and 

 continue to select. 



Variability versus Uniformity. High excellence is not 

 correlated with uniformity of production, as the Oregon 

 experiments show (page 111). Breed improvement does 



