Ranunculus Bulbosus Semiplenus. 247 
I conclude, therefore, that in this case the half race 
cannot be transformed into the double race by simple 
selection, but only by an internal change a mutation 
the external causes of which are still unknown to us. 
Proceeding now to the detailed description of my 
experiment, I begin with the half race in the conditions 
in which I originally found it in nature. 
I found the half race growing in 1886 and 1887 in a 
sunny and sandy spot not far from Hilversum, where I 
have often seen it since. The bulbous buttercup grew 
there in abundance ; most of the flowers were normal, 
but a considerable number had more than five petals. 
I shall refer to these latter for convenience of expression 
as pleiopetalous. 
For several years I have recorded the flowers in that 
locality. I give the records of 1886 and 1887, each of 
which relate to 300-400 flowers. The data are given as 
percentages. 
Number of petals 5 6 7 8 9 10 11 12 13 14 
Flowers in 1886 91.5 5.5 1.2 0.6 0.6 0.3 0.3 
Flowers in 1887 90 7 2 0.5 0.5 
The two series 1 agree as closely as could be expected 
and the records for the other years also fall in line. The 
maximum of the curve (see Fig. 51 H) is over the 
normal number of petals ; and from it the curve falls 
rapidly. It is a so-called half GALTON-curve. Flowers 
with less than five petals do not occur in this locality. 
The great steepness of this curve is due to the fact 
that on many of the plants no pleiopetalous flowers were 
found on the days when the observations were made. 
But this does not mean that the half race is mixed with 
1 Ueber halbe Galton-Curven ah Zeichen discontinuirlicher Varia- 
tion. Ber. d. d. bot. Gesellschaft, Vol. XII, 1894, p. 197, where some 
of the series of figures given below can also be found. 
