VII DOMINANCE 71 



been shown that in such a family some of the birds 

 without the extra toe may nevertheless transmit the 

 peculiarity when mated with birds belonging to 

 strains in which the extra toe never occurs. Though 

 the external appearance of the bird generally affords 

 some indication of the nature of the gametes which 

 it is carrying, this is not always the case. Nevertheless 

 we have reason to suppose that the character segregates 

 in the gametes, though the nature of these cannot 



Fig. 15. 

 Fowls' feet. On the right a normal, and on the left one with an extra toe. 



always be decided from the appearance of the bird 

 which bears them. 



There are cases in which an apparent irregularity 

 of dominance has been shown to depend upon 

 another character, as in the experiments with sheep 

 carried out by Professor Wood. In these experi- 

 ments two breeds were crossed, of which one, the 

 Dorset, is horned in both sexes, while the other, the 

 Suffolk, is without horns in either sex (cf Plate III.). 

 Whichever way the cross was made the resulting Fj 



