No. 4.] HEREDITY AND THE DAIRY COW. 9 



which thej are combined. In all the higher animals, at 

 least, every individual brings together the characters of two 

 separate individuals, and this combination will never be an 

 exact reproduction of either one of the parents. In this way, 

 we get a great diversity in families. 



It might be supposed, however, that the successive off- 

 spring of any two individuals would all be exactly alike. 

 This we know is not the case from every-day observation. 

 Everywhere about us we see children from the same parents 

 that are unlike in ]:)hysieal and mental constitution, and 

 the same is true of the lower animals. This brings us to a 

 brief consideration of the structure of the germ cells which 

 produce the individual. 



The microscope has revealed the fact that the cells of all 

 living' things are complex in their make-up. Without at- 

 tempting to prove the statement at this time, it is sufficient 

 for our purpose to say that the majority of scientists believe 

 that the characters of the individuals are represented by ac- 

 tual physical factors in the germ cells ; that is to say, if. the 

 animal is to possess horns, there is present in the germ cell a 

 factor which causes horns to grow at the proper time, and the 

 same is true for different colors, functions, etc. 



Each of the parents possesses these various factors, and 

 when they are joined together in the germ cells they do not 

 l)lend into one factor made up of the qualities of both, but they 

 exist together, as it were, side by side in a sort of partner- 

 ship in which one factor may be dominant over another. For 

 instance, if a pure, white-faced Hereford is bred to a ])ure 

 polled Durham, which has a red face, the resultant offspring 

 will have a white face.^ The factor for red is there because 

 the cells are there from the red-faced parent, but the red 

 does not show in the offspring because in this partnership 

 the white is dominant over the red. Why this is so we cannot 

 tell ; we only know that it is so by actual experiment. The 

 red is not lost, however, because we find that if we breed the 

 hybrids together, some of the offspring of this second genera- 

 tion will have red faces. This shows that the factors for red 



1 For clear explanation of the Hereford- Durham cross, see article by J. W. Spillman in 

 Vol. v., American Breeders' Association. 



