BREEDING 111 



In practice a period of at least three weeks is necessary 

 to rid the oviduct of active spermatozoa and insure a cessa- 

 tion of the influence of a previous mating. 



Influence of Previous Impregnation. — ^The fact that eggs 

 remain fertile for days and even weeks after the removal 

 of the male, combined with other circumstances, has led 

 to a somewhat common belief that the influence of an impreg- 

 nation is often permanent. A common illustration is found 

 in the idea that if a pure white hen is once mated with a pure 

 black male the offspring of a subsequent mating with a pure 

 white male, which may occur the following season or even 

 two or three years later, are likely to show black feathers, 

 as the result of the previous mating with the black male. 



As a matter of fact, black feathers are a frequent occur- 

 rence in the offspring of pure white birds that have never 

 been mated with anything but pure white birds. All efforts 

 to produce an increase in the number of black feathers of 

 offspring of a white hen mated with a white male, but which 

 had previously been mated with a black male, have failed. 

 With other animals all efforts to secure a permanent influence 

 of any sort from a previous impregnation have uniformly 

 failed. There is no reason to believe the results would be 

 otherwise with fowls. 



Maternal Impressions. — In chickens the claims of prenatal 

 influence or the registering of maternal impressions are 

 largely confined to color. One not infrequently hears the 

 claim that yellow-painted buildings about the premises 

 where the fowls spend much of their time tends to induce 

 creaminess or brassiness in the feathers. If such an influ- 

 ence is possible why have not all birds become green through 

 looking at the grass and trees. 



Experimentally, it has been impossible to produce such 

 effects. ^ Brassiness seems to appear only when fowls are 

 allowed to be in the sun. It is possibly a sort of sunburn. 

 Creaminess is usually the result of oil in the feathers and may 

 be increased by feeding yellow com freely. 



In this connection it should be clearly understood that 

 while maternal impressions do not appear in the offspring 

 in kind, both the matei-nal and paternal vigor and physical 

 thrift have very much to do with thrifty offspring. 



