ANTHOCYANINS AND GENETICS 187 



standards. No red hooded individual was found. Also in the cross 

 between a dark-axilled plant with sterile anthers (Df) and a light- 

 axilled plant having normal anthers (dF), i.e. the converse of the case 

 quoted above, no sterile light-axilled plants were found. 



As previously mentioned, the repulsion cases were originally thought 

 to be total, and, on consulting the above table, it will be seen that, 

 unless the repulsion is of small intensity, the form aabb is very rare. 

 There is, however, some evidence that the case of blue colour and long 

 pollen is of the 1 : 7 order. This case is the reverse of that quoted 

 above and occurs in the F 2 from the cross Bl x bL. One red round- 

 pollened plant was found in 419 individuals. The coupling, as we have 

 seen, is on the 7:1:1:7 system. The coupling between blue and erect 

 standard, i.e. from BE x be, is of the 127 : 1 : 1 : 127 system, so that 

 if there should be the same intensity in the coupling and repulsion 

 systems, the number of plants required to give 1 hooded red would be 

 65,536, which would lead to the impression first gained, i.e. that there 

 is total repulsion. 



Gregory (558) has also discovered a case of coupling in Primula 

 sinensis between magenta colour and short style, which are dominant 

 respectively to crimson colour and long style ; the case is on the 7 : 1 

 system. There is also evidence of partial coupling with a third factor 

 which suppresses the development of pigment in the stigma, giving 

 rise to the dominant green stigma. Yet another instance of complete 

 repulsion is that between the above-mentioned factor suppressing 

 colour in the stigma and a factor suppressing colour in the stem. 

 Thus a heterozygote from L stem r stigma x g stem g stigma gave 

 no plants with red stem and red stigma. 



It is not proposed here to enter further into the complexities of 

 the question of reduplication though one more point may just be 

 mentioned. In a recent paper 1 , Trow has suggested a distinction 

 between what he calls primary and secondary reduplication series. 

 Thus, he says, if we take a case of three factors, A, B and C, where 

 there is reduplication between A and C of the form n : 1 : 1 : n, and 

 between A and B of the form m : 1 : 1 : m, then the secondary form of 

 reduplication derived from these primary ones, and denoting the relation 

 between B and C, has theoretically the form 



nm + l:m + n:m + n: nm + 1. 



Experimentally this hypothesis appears to fit the above-mentioned 



case occurring in Primula sinensis (Gregory, 558) between the three 



1 Trow, A. H., 'Forms of Reduplication,' J. Genetics, Cambridge, 1913, n, pp. 313-324. 



