C. J. Bond 117 



coloured animal having two blue or two yellow eyes resulted in the pro- 

 duction of both asymmetrically and symmetrically pigmented offspring. 



Przibram concludes that asymmetric animals can be traced back to 

 asymmetric ancestry. The asymmetry can also be altered during 

 hereditary transmission, thus either eye colour of the asymmetric 

 parent can appear in the symmetric form in the offspring. 



The conditions (genetic) under which asymmetry of eye colour first 

 appears are unknown. 



Association between eye colour pattern and skin or coat colour 

 pattern. 



Recent researches by Pearson, Nettleship and Usher on albinism 

 in man (8) show that the piebald, that is the black and white skin 

 colour pattern, does occur though rarely in individuals belonging to the 

 coloured races of mankind. In some of these cases of piebald negroes 

 a familial association with complete albinism has been traced, in others 

 with leucoderma and some other conditions having a pathological or 

 somatic origin. 



On the other hand a piebald skin colour, apart from pathological 

 conditions, has not (so far I believe) been recorded among European 

 races. This may be due to the fact that no systematic search has been 

 made for this condition. 



Some authorities, A. R. Gunn(13), are of opinion that partial albinism 

 does occur among Scotchmen but in these, as in some cases of partial 

 albinism, the dissociation is between eye colour and skin and hair 

 colour, rather than between different areas of skin colour, though the 

 important fact that albinos of different strains may carrj* different 

 pattern factors is suggestive. 



Thus, although a considerable number of cases of partial or complete 

 heterochromia of the iris occur during the inter-breeding of duplex with 

 duplex, and duplex with simplex types of eye colour, no cases of piebald 

 skin colour have been recorded so far as arising during the inter-breeding 

 of light complexioned and dark complexioned European varieties. 



If some segregation of skin colour factors does occur in sub- 

 sequent gametogenesis in the offspring of mulatto hybrids as stated 

 by some observers, even in such cases the segregation process would 

 seem to affect the self-colour patterns as a whole. 



In this respect then the black and white human hybrid (mulatto) 

 and the pied animal hybrid, e.g. the Dutch or Orkney rabbit, are 

 dissimilar. 



