An Introduction to a Biology 



We start with a pink-eyed mouse with a colourless coat 

 (which we may denote for brevity's sake by the formula 

 00), the albino, and mate it with a mouse which is also 

 pink-eyed but has a partially-coloured coat (which we may 

 call 00), and get as a result a black-eyed mouse with a 

 fully-coloured coat (which we may call CC). So much for 

 the nature of the hybrids as far as colour is concerned. Now 

 for their progression. The hybrids never waltz. This is true 

 of the hundreds that I have raised. 



Let us now consider the result of mating these hybrids 

 together. First with regard to colour. The offspring pro- 

 duced by the union of these hybrids fall into the three cate- 

 gories 00, 00, and CC, in the proportions 25, 25, and 50 

 per cent, respectively. That is to say, in point of colour, 

 on the average one mouse in every four is like its albino 

 grandparent ; one in every four like its waltzing grand- 

 parent ; and two in every four like their parents the hybrids. 

 It should be mentioned that all mice falling into the category 

 00, for example, are not exactly like the Japanese waltzer 

 in colour. For example, the fawn colour may extend over 

 the whole body ; or, again, a new colour, lilac, may arise, 

 associated with pink eyes, in this generation. So long as a 

 mouse has pink eyes and some colour in its coat it is reckoned 

 as belonging to the category 00. But the number of colours 

 that can co-exist in a mouse with pink eyes is limited ; for 

 example, neither a dark grey nor a black mouse ever has 

 pink eyes. 



Now let us look at the posterity of the three kinds of mice 

 denoted by the formulae 00, 00, and CC. OO's, i.e. albinos, 

 when mated together produce only albinos ; OO's also when 

 paired breed true with very rare exceptions ; while the off- 

 spring of CC X CC fall as before into the three categories 

 00, 00, and CC in proportions which I have not yet 

 determined. 



The inheritance of colour in this case is shown at a glance 

 in the following Table : 



208 



