THE PROBLEMS IN MATING AND IN EGG PRODUCTION 119 



of the tails to one of the dwarfs, and the number of tails that 

 produced some dwarfs was two to one. 



The diversity of characters which followed the laws of trans- 

 mission appears before our eyes every day in observing the 

 progeny of birds we breed by the character produced in feather 

 pattern — from the feathers and of comb. 



Mendel taught that in each gamete there was either a 

 definite faculty for the production of a recessive chai^acter or a 

 dominant character These he called factors. These factors, 

 then, may be considered the unit characters which appear in 

 the development of the zygote. 



Bose R +P Pei 



I 1 



W W" Ft Generatic 



^A/ E P 3 -FzGeneration 



^ -3 3 r 



Fig. 42. — Mendel's chart showing the result of breeding various varieties 

 of combs of fowl, ij, Rose comb; P. pea comb; ^^' , walnut comb; 5, single 

 comb. 



In our example above tallness in the pea would be considered 

 a unit character, therefore the gametes containing this unit 

 character contain the factor for the production of tallness. 



Thus, in the structure of the feather we find the shape of the 

 common type feather formed by barbules holding together the 

 barbs preserving the usual shape. In the silky fowl the bar- 

 bules are absent, and the barbs without support ai'e not held 

 together and a silky coat presents ixself. This silky condition 

 is recessive. 



In the production of the proper comb the breeder is con- 

 stantly battling in an effort to secure and fix the proper unit 

 character or factor. 



Thus, experiments have shown that the rose comb is 

 dominant in the ordinary way to the single comb, such as 



