94 Experiments with Primula sinensis 



continued, and the totals for the last three years are 972 small-eyed, 

 326 large-eyed {expectation : 973-5 : SH^-'S). It is therefore impossible 

 to attach any great importance to the discrepancy in the early years, 

 though at the same time it remains unexplained. 



(2) White eye x small yellow eye. 



The white-eyed race ("Queen Alexandra") is a recent addition 

 to my collection and only a few F„ families have been raised from 

 crosses in which it takes part. 



The heterozygote resulting from the cross with a small-eyed race 

 can be distinguished, on close examination, from the pure " Queen 

 Alexandra" by a faint appearance of yellow or yellowish-green, which 

 is most pronounced on the rays con-esponding with the median line of 

 each petal (Plate XXXII, fig. 62, No. 3.5/9)'. Three F„ families have 

 been raised from the self-fertilized hybrid, and have given 1S2 white 

 eye and heterozygous, 67 small yellow eye {expectation : 186-75 : 63-25). 



(3) White eye x large yellow eye. 



The heterozygote resulting from this cross is not distinguishable to 

 the eye from that of the preceding case (Plate XXXII, fig. 62, 

 No. 36/9). The one Fr, family raised from the hybrid by self- 

 fertilization has given 52 white eye and heterozygous, 12 large yellow 

 eye {expectation : 4-^ : 16). An attempt to separate the pure from the 

 heterozygous white-eyed offspring gave 19 with no trace of colour in 

 the eye, 33 with faint yellow rays. 



Colour. 



The various forms of red stem, and the colours of the flowers, are 

 due to the presence of coloured sap. Both in the stem and in the 

 flower the simple colour may be modified by the action of numerous 

 factors which affect its distribution, intensity and tint. There is a close 

 relation between the colour of the flower and that of the stem, in that 

 fully coloured flowers are only produced by plants having fully coloured 

 stems. The deepest colour in the flowers of a green-stemmed plant 

 is that exhibited by the pale pink strain known as " Reading Pink " 

 (Plate XXX, fig. 13), while the white-edged type exemplified in " Sirdar " 

 is characteristic of plants in which the stem-colour is re.stricted to the 



• The contrast between the yellow rays and the white i,'rouud is somewhat intensified 

 in photographic reproduction. 



