212 Varietäten, Descendenz, Hj r briden. 



Keeble, F. and Miss C. Pellew. White Flowered Varieties 

 of Primula sinensis. (Journ. Gen. I. p. 1—5. 1910.) 



Gregory, R. P., Experiments with Primula sinensis. (Journ. 

 Gen. I. p. 73—132. 3 pl. (2 coloured). 1913.) 



It will be convenient to deal with these two papers together, 

 since they are to some extent complementary to one another as 

 regards observations on the inheritance of colour in Primula sinensis. 



The colour in the stems and liowers of P. sinensis is due to 

 the presence of coloured sap and presumably results from the in- 

 teraction of two complementary factors. Flower-colours may be 

 divided into two classes, namely, 1) füll colours, which are found 

 only in plants having fully coloured stems; and 2) pale colours, 

 which occur only in plants with green or very feebly coloured 

 stems. White flowers may be associated with stems of any kind. 



Besides the ordinary types of self-coloured flowers, there occur 

 various flaked or striped varieties, as well as a peculiar type known 

 as "Sirdar", in which the pigmcnt of the flower occurs in minute 

 dots and the edges of the petals are white. This type of flower is 

 invariably associated with stems which have pigment only in the 

 bases of the leaves and petioles, the rest of the stem and leaves 

 being green. The inheritance of the "Sirdar" character may be 

 described conveniently if the "Sirdars" be looked upon as belonging 

 to the fully coloured series, while they lack a factor, the presence 

 of which is required to bring about the even distribution of the 

 colour. 



When the albino "Snowdrift" is mated with a fully coloured 

 type, the F 2 contains only one real albino in every 16 offspring. 



Füll flower-colours are divisible into three classes, namely, 

 1) shades of magenta, 2) shades of cnmson and red, 3) shades of 

 blue. Füll colours are dominant to pale colour, and, of the füll 

 colours, magentas are dominant to reds, and both magentas and 

 reds are dominant to blue. Plants having pale flowers may carry 

 the factor for magenta, but the colour oftheir flowers isindistinguish- 

 able from that of similar plants which lack the magenta factor. 



White flowers may be dominant or recessive to coloured. Green- 

 stemmed whites may be dominant or recessive whites; most of the 

 red-stemmed whites which have been examined have been found 

 to be dominant whites, the only exception yet known being Keeble 

 and Pellew's race of "Snow King", Dominant whites are white in 

 virtue of the suppresion of colour in the flower; they may possess 

 the factors for flower-colour and in that case give coloured offspring 

 in F 2 when mated with the albino '"Snowdrift". 



Partial or complete suppression of colour by dominant factors 

 is a common phenomenon in P. sinensis. Some of the factors affect 

 the colour of the flower only; one, at least, affects the colour of 

 both stem and flowers. 



The phenomena of the suppression of flower-colour are compli- 

 cated by the fact the Operation of two distinct factors, affecting 

 distinct areas, can be separately traced. Of these factors, one affects 

 the peripheral parts of the corolla, the other the gynoecium and 

 central part of the flower. The second factor is present in the nu- 

 merous races which have coloured flowers and green Stigmas. 



Various light shades of colour are dominant to darker shades, 

 both in the stem and flower. 



As in several other cases the genetics of the flaked or striped 

 types cf pigmentation present certain peculiarities, which are not 



