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of selecting favourable birth variations could not possibly
have been pursued. If the organism were only able to
adapt itself to external conditions through the action of
Natural Selection, differences of colour sufficiently great
to constitute a specific difference would require some little
time to be produced. But in the following case an indi
vidual assumes one or other of three differently coloured
garbs, according to the colour of the flower it frequents.
Now, whatever you may call this process, and by what
ever means it may be achieved, it is certain that it is
not Natural Selection, and that sexual reproduction and
struggle for existence do not account for the transmutation.
“ M. E. Heckel, of Marseilles, has recently described an interest
ing case, which may be frequently seen in the South of France.
The spider, Thomisus onus/us, is often found in the flowers of
Convolvulus arvensis, where it hides itself for the purpose of snaring
two Diptera, Nomioides minutissimus and Melithreptus origani, on
which it feeds. Convolvulus is abundant, and three principal colour-
variations are met with : there is a white form, a pink one with
deep pink spots, and a light pink form with a slight greenish
ness on the external wall of the corolla. Each of these forms is
particularly visited by one of three varieties of Thomisus. The
variety which visits the greenish form has a green hue, and keeps
on the greener part of the corolla ; that which lives in the white
form is white with a faint blue cross on the abdomen and some blue
at the end of the legs ; the variety which lives in the pink form is
pink itself on the prominent parts of the abdomen and legs. If the
animal happens to live on Dahlia versicolor, the pink turns to red,
and if it lives in a yellow flower—Antirrhinum majus, for instance—
it becomes yellow. At first, Professor Heckel supposed the three
varieties of Thomisus to be permanent, but he discovered accidentally
that any one of these peculiarly coloured spiders, when transferred
to a differently coloured flower, assumes the hue of the latter in the
course of a few days ; and when the pink, white, green, and yellow
varieties are confined together in a box, they all become nearly
white.”—(Nature. vol. xliv., p. 451.)
Prince Kropotkin, in reviewing the result of recent
investigations, asserts that they go to show that the varia
tions are not accidental; meaning thereby, it is to be