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tion, the first hybrid generation consisting usually 

 of reversionary forms. In this class of cross nothing 

 must be expected from the immediate result of the 

 cross. Nothing, for instance, could be more dis- 

 appointing to the mouse fancier than the result of 

 crossing the albino with the Japanese waltzing mouse 

 — namely, an animal scarcely distinguishable from one 

 that could be caught in a trap, any day, in the pantry. 

 Yet I know no more beautiful colour in an animal 

 than that of the " lilacs " which are produced in 

 small numbers by mating these hybrids of the first 

 generation together. I am given to understand that 

 this colour is new to the " fancy," but I do not 

 know if there is a class for it at the shows. 



It is very important to keep these two ways in 

 which novelties are obtained by crossing, distinct in 

 the mind. In the " first generation method," as it 

 may be called, an unstable new form is the immediate 

 result of the cross ; and to obtain it again it is better 

 to repeat the cross than to breed these hybrids 

 together, partly because by this means 100 per cent, 

 of the offspring are of the desired kind (as opposed 

 to the 50 per cent, produced by mating the first 

 crosses together) ; and partly because of the greater 

 vigour of first crosses. In the " second generation 

 method," as it may be called, a stable new form is 

 obtained in the second hybrid generation ; the hybrid, 

 which is usually reversionary, is useless in itself, and 

 merely serves as a sort of mill which will turn out 

 any desired quantity of the new forms. 



The two methods are like the two chief methods 



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