362 EXPERIMENTAL STUDY OF INHERITANCE 



Darbishire has obtained many results which harmonise well 

 with Mendelian theory, while others require some ingenuity if 

 they are to be fitted in with this interpretation. As a good case 

 we may cite one where the inbreeding of pigmented mice — 

 derived from crossing pigmented and albino individuals — yielded 

 159 pigmented young and 55 albinos (53-5 being the theoretical 

 anticipation). When similar hybrids were paired with pure 

 albinos, they yielded 69 pigmented and 69 albino forms, pre- 

 cisely as the theory would lead us to expect : 



D R 



D(R) 

 D(R) 



ID + 2D(R) + iR 

 x 



2R 



D(R) R 



Cuenot crossed an albino AG (with latent grey) with an 

 albino AB (with latent black), and obtained albinos (AGAB). 

 He crossed a black mouse CB with an albino AY (with latent 

 yellow), and obtained }^ellow mice (CBAY). He then paired 

 AGAB (albino) with CBAY (yellow) and obtained 151 young— 

 81 albinos, 34 yellow, 20 black, 16 grey ; the theoretical an- 

 ticipation being — 76 albinos, 38 yellow, 19 black, 19 grey. 

 This is an exceedingly striking and convincing case. 



Waltzing Mice. — The mice of this interesting Japanese breed 

 have among other peculiarities the habit of waltzing round in 

 circles. When waltzing mice are crossed with normal mice, 

 their abnormal quality behaves as a recessive. 



Guinea-pigs. — If a black guinea-pig of pure race be crossed 

 with a white one the offspring will be all white, and if these are 

 mated with each other the recessive white character reappears 



