406 
Cooperative Tnrestigations on Plants 
(d) Colour of Middle Third of Petal. We have the following results : 
Parkstone General Parkstone Mothers 
Population of Crewe Crop 
Some red in Petal* 240 153 
All Pink ... 481 161 
Some White ... 252 94 
973 408 
Or, in percentages : 
Some red in Petal 24-7 37 '5 
All Pink ... 49-4 39-5 
Some White ... 25-9 23-0 
Taking the all pink as our reference group we have 
d = V0m2a' =VSSl^a, 
or /J, = a' / a = V2Q06. 
In other words, there has been such a selection of red mothers that the mothers 
are w;o?'e variable than the general population at Parkstone. The mean poppy, 
which in the general population is about half-way f up the pink range, has in the 
maternal plants crept nearly up to 1/8 from the beginning of the red groupj. 
If we turn to the Crewe offspring we find the following values: 
Mothers Daughter Plants 
153 37-5 p.c. 139 34-1 p.c. 
161 39-5 p.c. 199 48-8 p.c. 
94 23-0 p.c. 70 17-1 p.c. 
408 408 
Thus we see regression towards the pinks. In terms of d the pink range we 
have for cr" the standard deviation of offspring 
a" X 1-3586 = c^, 
or a/a" = 102 nearly. Thus the variability of the general population at Crewe is 
sensibl}^ the same as that of the general population at Parkstone, but the mothers 
who provided germinating seed at Crewe were redder than the average Parkstone 
poppy, and the resulting offspring, though still regressing slightly towards the red, 
are yet about ^ off the boundary of the red §, instead of half-way across the pink 
range as in the Parkstone crop. 
The exact interpretation of this inverted selection is difficult, and has not yet been 
theoretically worked out. The formula on p. 404 involves approximate normality 
of the distribution, and becomes meaningless when the selection curve does not 
theoretically fall ivliolly inside that of the population from which selection takes 
place. The distributions of colour percentages at Kidderminster and Arncliffe are : 
Some Red All Pink Some White 
Kidderminster ... 34-5 40-0 25-5 
Arncliffe ... 33-8 40-4 25-8 
* The two groups include under red 14 and 2 flowers respectively, which were noted to have a certain 
amount of white with the red or red-piuk. 
t -6851 to 1-3315. X -3186 to 1-0562. § -4106 to 1-3586. 
