110 



Experiments with Primula sinensis 



of short-style and the magenta colour has been revealed. In the F^s, 

 bred from plants heterozygous for both characters, the salmon-pinks 

 are invariably short-styled. The results clearly indicate complete 

 repulsion in gametogenesis between the two dominant factors, short- 

 style and magenta. The case is dealt with fully on p. 125. 



Rosy-Magenta. For the strain of this colour with which experi- 

 ments have been made I am indebted to Messrs Sutton. Very similar 

 types appear, as part of the magenta class, in the F^^a of certain crosses 

 between reds and either "Snowdrift" or pale-pinks carrying magenta. 

 The colour of the root-stock in this race bears the same relation to the 

 colour which appears in the ordinary magentas as does the flower- 

 colour in the two cases. The cross with " Snowdrift " gives an F^ of the 

 ordinary magenta type. In the F^ the rosy-magentas take the place 

 of the reds, but the distinction between the two classes is of course less 

 obvious than that between magentas and reds. Like the salmon-pink, 

 the rosy-magenta does not carry the factor for faint colour in the stem, 

 and in the light class the stems and roots are devoid of coloured sap, so 

 far as can be seen. The F^ obtained in one experiment of this kind 

 suggests a ratio of 9 magentas : 7 rosy-magentas, the numbers obtained 

 being : 



Full colours 



' Sirdars ' 



No colour in stem 



Reference 

 Number 



9/9 



Magenta 

 37 



Rosy- 

 magenta 



22 



Magenta 

 14 



Rosy- 

 magenta 



10 



Pale- 

 pink 



14 



White 

 4 



In the next two, however, the usual 3 : 1 ratio obtains : 



Full colours "Sirdars" No colour in stems 



Totals 



81 



32 



30 



40 



One can scarcely believe that the result shown in Experiment 

 No, 9/9 is only a fortuitous departure from the 3 : 1 ratio, nor does it 

 seem likely that it is due to experimental error in the separation of the 

 classes, for both No. 9/9 and No. 23/9 were recorded within a day 

 or two of one another, and in each case the separation of the classes 

 was confirmed by another observer. The same rosy-magenta parent 

 was used in Experiments 9/9 and 23/9, and one of its offspring in 

 Experiment 17/10. The different results are not necessarily con- 

 tradictory, for if the difference between magenta and rosy-magenta 



