388 SECTIONAL TRANSACTIONS.—D. 
Prof. G. D. Hate Carpenter.—Charles Darwin and entomology (3.10). 
Galapagos insects. Similar habits of ant-lions in Australia and Europe 
suggest unity of creation in 1836: by 1845 view-point changed. Colour- 
ation of insects formerly ascribed to need for concealment : bright colours 
resembled flowers. Unpleasant odours repelled enemies: no one correlated 
this with conspicuousness and peculiar habits. Bates in 1862 described 
resemblances of butterflies to others, not nearly related, conspicuous 
and avoided by enemies, as ‘ Mimetic Analogies’ produced by Natural 
Selection. Reason for conspicuousness explained in 1867 by Wallace for 
brightly coloured caterpillars on appeal by Darwin. Natural selection 
explains (1) association of conspicuous colouration with habits displaying it, 
toughness, and repugnant qualities ; (2) acquisition of conspicuousness by 
a form lacking the other qualities ; (3) why mimicry deceives the artist and 
not the anatomist, and (4) production of mimetic effect by different means. 
Coincidence, affinity, or similarity of environment cannot explain niceties of 
geographical distribution of model and mimic. 
Observations and experiments on insectivorous vertebrates show pre- 
ferential feeding according to demands of theory. 
Darwin stressed insects as exemplifying sexual selection, but elaborate 
scent-producing apparatus in males, acrobatic performances, and pre- 
sentation of gifts to females provide little evidence of preferential choice 
by female of one particular male. 
Modification of whole groups of insects and flowers for mutual benefit 
strong argument for natural selection. 
Prof. E. W. MacBripg, F.R.S.—Darwin and the problem of the population 
of the Galapagos Islands (3.30). 
Darwin’s reputation as a naturalist and a great observer seated be secure 
if it rested on his description of the Galapagos Islands alone. In a masterly 
chapter in The Voyage of the Beagle he makes these islands live before our 
eyes. We see their arid burnt surfaces of lava studded with innumerable 
cones ; the great tortoises and the hard beaten paths which they pursue in 
their search for water; the two peculiar lizards obviously nearly related 
and unlike the Iguanas, but one clearly adapted for life in water and the 
other for life on land; we recognise the curious fact that the main islands, 
so closely similar in their physical features, are inhabited by species of 
birds and insects closely allied but nevertheless differing in the different 
islands. 
In The Voyage of the Beagle he speculates on the mystery of exe 
remote islands having been centres of so much creative activity, but 
in The Origin of Species he puts forward as an explanation ‘ Natural 
Selection.’ At another meeting of this section I have maintained that this 
explanation really resolves itself into falling back on ‘ chance’ as a cause, 
and such a course I regard as unscientific. But the only alternative course 
is to suggest reaction to the environment as the cause of specific characters, 
and it might be asked how environment differs in such similar islands. 
Darwin suggests the existence of different proportions of enemies, but this 
is in the highest degree unlikely. A precisely similar phenomenon was 
described by Kammerer in his description of the varieties of lizards in- 
habiting the rocky islets of the Adriatic. He shows that in one islet the 
male has a rosy flush on the breast in the breeding season, and in another 
during the whole of the year, and yet there are no natural enemies as 
far as Kammerer could discover. One islet is more washed by spray than 
the other, that is all the difference that could be discovered between them. 
