364 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) 



X 



D(R) 



I D + 2 D(R) + I R 



X 

 2R 



D(R) R 



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

 albino y4B (with latent black), and obtained albinos (y4G.4B). 

 He crossed a black mouse Q,B with an albino AY (with latent 

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

 /IG/IB (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. — In this well-known breed of fancy mice, only 

 one of the three semicircular canals of the ear attains to develop- 

 ment, and this abnormality is associated with the peculiar habit 

 that the animals ' ave of waltzing round in circles. When waltz- 

 ing mice are crossed with normal mice, their abnormal quality 

 behaves as a recessive. 



Rats. — The results reached by breeding rats seem to be more 



I 



