78 
DARWINISM 
CHAP. 
remarkable facts as to their variability. He declares that on 
the same branch of oak he has noted the following variations : 
(1) In the length of the petiole, as one to three ; (2) in the form 
of the leaf, being either elliptical or obovoid ; (3) in the margin 
being entire, or notched, or even pinnatifid ; (4) in the ex¬ 
tremity being acute or blunt; (5) in the base being sharp, 
blunt, or cordate; (6) in the surface being pubescent or 
smooth; (7) the perianth varies in depth and lobing; (8) 
the stamens vary in number, independently; (9) the anthers 
are mucronate or blunt; (10) the fruit stalks vary greatly 
in length, often as one to three; (11) the number of fruits 
varies; (12) the form of the base of the cup varies ; (13) the 
scales of the cup vary in form; (14) the proportions of the 
acorns vary ; (15) the times of the acorns ripening and falling 
vary. 
Besides this, many species exhibit well-marked varieties 
which have been described and named, and these are most 
numerous in the best-known species. Our British oak (Quercus 
robur) has twenty-eight varieties; Quercus Lusitanica has 
eleven; Quercus calliprinos has ten; and Quercus coccifera 
eight. 
A most remarkable case of variation in the parts of a 
common flower has been given by Dr. Hermann Muller. He 
examined two hundred flowers of Myosurus minimus, among 
which he found thirty-five different proportions of the sepals, 
petals, and anthers, the first varying from four to seven, the 
second from two to five, and the third from two to ten. Five 
sepals occurred in one hundred and eighty-nine out of the two 
hundred, but of these one hundred and five had three petals, 
forty-six had four petals, and twenty-six had five petals ; but 
in each of these sets the anthers varied in number from three 
to eight, or from two to nine. We have here an example of 
the same amount of “ independent variability ” that, as we 
have seen, occurs in the various dimensions of birds and 
mammals; and it may be taken as an illustration of the kind 
and degree of variability that may be expected to occur 
among small and little specialised flowers. 1 
In the common wind-flower (Anemone nemorosa) an almost 
equal amount of variation occurs ; and I have myself gathered 
1 Nature, vol. xxvi. p. 81. 
