692 TRANSACTIONS OF SECTION K. 
the short-styled or thrum-eyed form being dominant over the long styled (pin-eyed) 
form. Subsequent experiments have confirmed this, and the larger numbers now 
obtained approximate closely to the theoretical ratios, although in particular cases 
discrepancies sometimes occur, 
In the case of one race of plants the results of our earlier experiments 
appeared to indicate an interesting departure from the normal. Used as male 
parents, these plants gave results consistent with the gametic constitution DD, 
while used as female parents they appeared to be heterozygous. This case has 
been followed up, but in all the offspring the peculiarity was found to have 
disappeared, all the plants used proving to be pure in respect of the short 
style (DD). 
Other characters which have been investigated are the form of the leaf, the 
presence or absence of the large yellow ‘eye’ in the flower, the colour of the stem 
and petioles, and the colour of the flower. 
Of these the first gives simple Mendelian results, the palmate character of the 
leaf being dominant to the fern leaf. In some cases a form of leaf somewhat 
intermediate in character between the palmate and fern-leaf types occurs. We 
conjecture that this type may be of a heterozygous nature. 
The large yellow ‘eye’ may occur in thrum-eyed or non-thrum plants. It is 
a recessive character, rendered interesting by the fact that when it occurs in 
a plant which is not a thrum the style does not project above the level of the 
anthers, although the position of the anthers and the size of the pollen, as well as 
the results of breeding experiments, prove it to be a long-styled plant. 
As regards the colour of the stem and petioles, both may he green, or red 
pigment may be present, which varies in intensity and distribution in different 
races. The red colour may be confined to a faint appearance of red round the 
‘collar,’ the stems being green; the stems may be light red, with or without 
a darker ‘collar’; or the stems and collar may be a deep red. The colour of the 
stem is therefore determined by two (and perhaps more) pairs of allelomorphic 
characters. 
The colour of the flowers presents a very complex problem, and we are still 
very far from its complete elucidation. Perhaps the most interesting result at present 
definitely attained is the discovery of two distinct classes of whites. One race of 
white-flowered plants with pure green stems (Sutton’s ‘Snowdrift’) proves to be 
a true albino, being devoid of any colouring pigment. But in all the other races of 
white-flowered plants examined a character occurs which must be looked upon as 
inhibiting the development in the flower of a colour which is potentially present 
in the plant. These white plants all show red pigment in the stem, although it 
may be confined to the merest trace of colour at the collar. 
‘Snowdrift’ crossed by a form with coloured flowers gives a coloured F,. 
The ‘Dominant Whites’ crossed by the paler colours give in F, white flowers, 
and crossed by the forms possessing full-coloured flowers give tinged white in F,. 
In F, these tinged whites break up into a long series of coloured, tinged, and 
white forms. 
The offspring of the ‘Dominant Whites’ x ‘Snowdrift’ possess white 
flowers (F,), and in F, give whites and coloured forms. The appearance of 
coloured flowers in F, may be explained from the gametic constitution of the 
parents. The ‘Dominant White’ possesses both inhibition and colour (DC) ; 
‘Snowdrift’ possesses neither (de). In the F, of such across three plants out of six- 
teen will be of the constitution (dC), and will therefore show colour in the flowers. 
The character of the colour depends on the particular race of ‘ Dominant White’ 
used in the experiment. From the results at present obtained one may perhaps 
say that when the ‘ Dominant White’ has a red collar only, the stems otherwise 
being green, the colour which appears in Fis a pale pink. When the ‘Dominant 
White’ is one which possesses deeper colour inthe stem, magenta-flowered plants, 
as well as pale-pinks, appear in F,. In both cases the pale-pink flowers are 
always borne on plants with red only in the collar, the magenta flowers on plants 
with red or full-red stems. 
This is an instance of the coupling between the colour of the flower and the 
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