168 
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