118 Expermients with Primula sinensis 



The " dominant white " parent of Nos. 26/6 and 30/6 was cue 

 which gives a very fully tinged F^ when crossed with " Crimson King " 

 — the coloured race with which 26/6 and 30/6 were mated ; the excess 

 of coloured offspring shown in their crosses may therefore be in part 

 due to experimental error, througii the inclusion of some deeply tinged 

 firms with the light colours, and in the absence of any other indica- 

 tions of departure from normal segregation one does not feel inclined 

 to attach any great weight to the discrepancy shown here. 



Dominant white x Coloured, red stigma. The F^ from this cross is 

 again a tinged white with green stigma (Plate XXX, fig. 18; Plate XXXI, 

 fig. 21). The F„ from one of these crosses — that between "Queen 

 Alexandra" and "Crimson King" — is illustrated in Plate XXXI, 

 figs. 22 — 43. As concerns the factors for inhibition, the i^, consists of 

 four classes, namely, (1) whites and tinged-whites, with green stigma 

 (Plate XXXI, figs. 22 — 26); (2) plants in which the peripheral part of 

 the corolla is white or tinged, the central part flushed, with red stigma 

 ("Duchess" and "Buller" types; figs. 27 — 31); (3) coloured, green 

 stigma (figs. 33, 34, 38 — 41); (4) coloured, red stigma (figs. 35 — 37, 

 42, 43). The four classes are in the proportions of 9 : 3 : 3 : 1, the 

 observed numbers being : 



White and tinned- •■ Duchess" and "' Buller" Coloured. Coloured, 



white, green stigma forms ; red stigma green stigma red stigma 



193 61 6-5 21 



E.rpniatioii 191-25 63-75 63-75 21-25 



" Ducltess." The "Duchess" types whicli appear in these i'Vs are 

 shown by experiment to be homozygous for the peripheral inhibiting 

 factor. Crossed with a coloured, red stigma, they give " Sir Redvers 

 Buller," which in turn gives "Duchess," "Buller," and fully coloured, all 

 with red stigma. The F., types resembling "Buller" are therefore those 

 which are heterozygous for the peripheral inhibiting factor. 



" Duchess " X green stigma. " Duchess," crossed with plants with 

 green stigma, gives a white or tinged-ivhite F^. The result is the same 

 whether the parent having the dominant green stigma be a coloured 

 form or a recessive white (" Snowdrift"), except that in the former case 

 the Fi has a rather deeper tinge. 



In certain cases the tiowers of the F^ have a distinct tinge of colour 

 in the corolla-tube, just below the region of the insertion of the anthers, 

 although no tinge at all may be discernible in the petals'. The charac- 



' A similar ebaracter lias been observed in one otber experiment where the f i from 

 (Dominant white x Crimson, green stigma) was crossed with a dominant white. In this 

 case the character was coupled with that of short-style. 



