10 
The Queensland Naturalist. 
VoL. 2 
reactions, which result in a synthesis of a dehnite compound 
or gi'oup of compounds, namely, nucleins.” 
Here may be appropriately mentioned the work of 
Poulton, who has shown that the colour of certain chrysalids 
is affected by the colour of surroundings, and may thus be 
either darkened or lightened at the will of the experimenter. 
A keen observer (Mr. H. Hacker), informs me that the species 
of Pediculus, or lice, common in South Africa, change from 
black to white, or vice versa, according to the colour of their 
host. In 11 cases out of 13, young flounders placed in an 
aquarium lighted from below showed the characteristic 
protective colouration on the lower and not on the upper 
side. In the abstract of the proceedings of the Linnean 
Society of New South Wales, October, 1913, there is noted 
an observation bv Dr. H. G. Chapman of Hyla coerulea, 
our common green tree frog, with the lower parts quite red, 
resting on the red leaf of a canna. There is an ever-growing 
amount of similar material recorded by numei'oiis 
investigators. 
Here I need make no apology for a parenthetical note : — 
In the history of humanity itself may we not trace responses 
to changes of environment. Take a slum child from dirty, 
unhealthy, and degrading surroundings ; feed, clothe, and 
educate him properly ; and he will in the generality of things 
respond to these stimuli. And there need be no wrangling 
in this case as to whether the impulse be mechanical or vital. 
But let us glance at the other side. Bergson is claimed 
by the vitalistic school, and his luminous writings have given 
a qualified support to a new form of that view. According 
to him the whole scheme of evolution suggests a grand 
elaboration of the life-force, working ever upwards through 
its own original creative impulse, and that the past is justifled 
in the present. Variations are not mere mechanical responses, 
but spring, to quote his own words, ” from the very effort 
of the living being to adapt itself to the circumstances of its 
existence.” This view, which may be summarised as a 
Neo-Lamarckism, is ca])able of admitting an internal psy- 
chological principle of development, although it is not bound 
to do so. Bergson claims that it accounts rationally for the 
phenomena of convergence, or the building up of identical 
complex organs on independent lines of development ; such 
as the eves of vertebrates, molluscs, and insects. 
Thus, to use Samuel Butler’s phrasing, the question 
largely resolves itself into a crux of luck or cunning. And 
an unbiassed observer may be tempted to assert that both 
factors are operating. Seemingly mechanical responses to 
external stimuli shed light upon, but do not altogether solve 
the problems of variation. Darwin’s words are still true 
