CONCLUSION. 



19 



guinea pig the three-coloured form. When we glance at the 

 enormous prolificacy of the domestic rabbit, guinea pig, and white 

 mouse, when closely confined under various climates, we may note 

 the comments of Darwin that in the Zoological Gardens some 

 rodents have coupled, but have never produced young ; some have 

 neither coupled nor bred, but a few have bred, as the porcupine, 

 more than once, the Barbary mouse, lemming, and the agati, several 

 times. The species, however, which has bred more than once in the 

 Zoological Gardens is the one which, perhaps, might have been least 

 expected, the flying squirrel, but the female never produced more 

 than two young at a birth ; when in her native American home she 

 bears from three to six young. What the zoologist now wants is 

 regular and accurate statistics of the numbers of young in wild and 

 tame rodents. If such a table induces the conclusion that sterility 

 is often induced by captivity, another fact will be gained for Darwin, 

 and my fancy mice will be an encouragement to their proprietor. 



" I have already stated what are the most common breeds of fancy 

 mice. I shall now proceed to show the method by which varieties 

 of cross colour may be produced almost at will, and how to enable 

 the practical mouse-fancier to obtain some of the reputed cross- 

 breeds. In this investigation it will be my duty to follow with some 

 care the statements of ' An Old Fancier,' and if it should be 

 found that our conclusions are not identical in any way, and that 

 my experience differs from his, I can only say that ' there is nothing 

 BO brutally conclusive as a fact,' and that mine have the advantage 

 of being able to appeal to witnesses and living specimens, whilst 

 the results I have obtained are precisely those which fit in well 

 with the theories alike of Broca and Darwin. Let me, therefore, 

 in order that my facts should be understood clearly, premise a few 

 extracts from my brood book. 



"The author I quote lays down as a principle that 'black and white 

 are obtained by crossing the two colours together. The same for any 

 two combinations of colour' (p. 11). This argument reminds one 

 of that of the counsel for the plaintiff in Stradling v. Stiles : ' What- 

 ever is black and white is pyed, and whatever is pyed is black and 

 white ; ergo, black and white is pyed, and vice versa, pyed is black 

 and white.' (' Pope's Works,' ed. 1824, vol. vii., 219). This 

 statement, of course, is traversed by Darwin in a passage I have 

 already given. Let me now test it by facts. 



"A. Both buck and doe black and white, nine young produced. 

 Two dead ; seven black and white. This was what we might have 

 expected. 



" B. Plum and white buck ; plum doe. Twelve produced. Five 

 dead ; three albinos ; four young grey self colour, that may with 

 maturer life prove to be plum colour, or may ' revert.' 



" C. Both buck and doe fawn and white. Nine young produced, 

 Three dead ; three fawn self colour ; three black. Here the white 

 colour in the parents is not indicated in the progeny, and in its place 

 a new black element is introduced. 



"D. Fawn and white buck; black and white doe. Seven young 



