134 RedupUcation in Mice 



The Fi generation consisted of 9G CE and (i cc, tiic CE's being 

 therefore of composition Ce . cE. 



They were mated together and produced 111 CE, 116 Cee or cc. 

 Of these latter 74 survived to giow hair and 33 were Cee, 41 cc. If 

 the rate of mortaHty is equal for Cee and cc, as Darhishire's figures 

 suggest, the original numbers were approximately HI CE, 5 17 Cee, 

 64-3 cc. 



If the gametic series of F^ was 1 CE : 1 Ce : I cE : 1 ce, the 

 expectation would be 9:3:4, or 127 7 CE, 426 Cee, .56-7 cc. If it 

 was 1 CE : 3 Ce : 3 cE : 1 ce, the expectation woidd be 33 : 1.5 : 16, or 

 117 CE, .53 2 Cee, 56'7 cc, a much closer fit. 



Darbishire mated his F^ to albinos, obtaining 378 CE, 368 cc, or 

 nearly equality. We mated F^ to CCee mice, obtaining 18 CE, 23 

 pink eyed, of which the 16 survivors were all Cee. This ratio suggests 

 equality. 



We next mated the F„ mice of composition cc (albinos) to those 

 of composition ee (pink tyed pigmented). We thus discovered 

 which albinos were ccEE, ccEe, and ccee, the former giving no Cee 

 offspring, the latter no CE, and similarly the Cee's were separated into 

 CCee and Ccee. Of the albinos 11 were ccEE, 9 ccEe, 6 either 

 ccEE or ccEe, 1 ccEe or ccee. Of the Cee's 7 were CCee, 11 Ccee, 

 4 doubtful. 



Having thus produced a number of Ccee mice (either F.. or 

 offspring of ccEe x CCee), they were mated together, and all their 

 albino offspring were therefore ccee. These were mated back to 

 the F-i. The result was 3 CE, 24 Cee or cc, of which 7 survivors 

 were cc. 



Supposing the gametic series to have been 1 CE, x Ce, y cE, z ce, 

 we have from the above matings : — 



\+x=y-\-z, and probably 1 + y = x + z, also x + y + z = ^. Hence 

 y = x, 2 = 1, and 2.r + 1 = 8, . •. a; = 3^. A.ssuming however that x = S, 

 the expectation from the mating F^ x ccee is 1 : 7 or 3f CE, 23| Cee 

 and cc, a close enough agreement, while without reduplication we 

 should expect 6|, 20i. 



The experiments are being continued and extended to rats. 



Part of our expenses were met by a grant from the Royal Society. 



