CHAPTER VI 



MENDELIAN HEREDITY {Continued) 



The Inheritance of Colour 



In the simple Mendelian cases discussed in the 

 last chapter the separate allelomorphic pairs were 

 described as Avholly independent of one another, and 

 in the manner of their inheritance this description is 

 correct for allelomorphic pairs in general except in 

 special cases, of which examples will be given later. 

 But although allelomorphs of distinct pairs are in- 

 herited independently, yet not infrequently they may 

 react upon one another so as to give an apparently 

 combined eifect in the individual bearing them. 

 This is especially, but by no means exclusively, 

 seen in the colour-characters of animals and plants. 

 In the list of examples of Mendelian characters it 

 was mentioned that coloured coat in animals or 

 coloured flowers in plants behave as an alternative 

 to whiteness (albinism, i.e. the absence of pigment). 

 But further analysis shows that the appearance of 

 colour depends upon the presence of at least two 



