1 84 Grossing the North and South African Ostrich 



Break 



The heterozygous condition with regard to the break is what would 

 be expected, assuming that the character is one which is in process of 

 introduction within the race, and that it behaves in Mendelian fashion. 

 At present the mutation is found in comparatively few individuals, and 

 in a state of nature there is little chance that a bird showing the break 

 would mate with another in a like condition, but rather with one having 

 the scales continuous. If the change first took place in a homozygous 

 duplex manner in a few individuals there is small likelihood that these 

 would mate with others in like condition, but with nulliplex individuals. 

 The first crosses would be dominant and simplex, and these mating with 

 other nulliplex birds would give half simplex dominants and half nulli- 

 plex, which is what the experiments indicate. As shown below, certain 

 significant results have been obtained on in-breeding some of the cross- 

 bred birds. 



TABLE X. 



Scutellation in F^ chicks comjiared with Parents and Grandparents. 



Parents : 



North African cock, No. 9 

 South African hen, No. 225 



Fi Crosses : 



Cross-bred cock. No. 182 

 Cross-bred hen, No. 179 



F2 Crosses : 



No. 1 



No. 2 ... 



No. 3 



No. 4 



No Break 



X 



Break 



