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could wake up in say a thousand years, we should be able to 
detect changes in the patterns of some butterflies. Although 
I am afraid the advance of science is not likely to be sufficiently 
rapid in our time for me to hold out any prospect of such an 
experience for any of you, there is every reason why we should 
afford this opportunity to posterity. A critical examination 
of the fragments of many species of butterflies captured ninety 
years ago by Burchell in 8. Africa, and gnawed to pieces 
during his Brazilian travels from 1825 to 1830, renders it 
probable, nay, almost certain, that with moderate care, insect 
pigments will endure for an indefinite period in our museums. 
One important justification for the great and permanent 
outlay required to bring together and maintain large collec- 
tions of insects is, that we are allowing our successors the 
chance of detecting and measuring the rate of specific 
change.* And, as I have already said, for this purpose the 
Lepidoptera stand pre-eminent. 
For the purpose of the inquiry this evening, our instances 
will be drawn from the Lepidoptera rather than other Orders 
of insects, because of the numberless examples of subtle 
distinction between forms which but yesterday, so to speak, 
became separate ; because of our knowledge, insufficient but 
considerable, of their geographical ranges; because of our 
experience, excessively imperfect and scanty, but still much 
larger than in other Orders, of inter-breeding and of descent 
from parent to offspring. 
First among the attempts to define species must be placed 
that which we rightly associate with the name of Linnzus. 
It has been admirably pointed out by the late Rev. Aubrey 
L. Moore, + that the dogma of the fixity of species is entitled 
to none of the respect which is due to age. “It is hardly 
credible to us,” he wrote, “that Lord Bacon, ‘the father of 
* Karl Jordan argues with great force in favour of specialisation in 
this direction by our museums. (See ‘“‘ Novitates Zoologice,” vol. iii, 
December 1896, pp. 431-433.) The Burchell collection from Brazil is 
only seventy-four to seventy-nine years old, but the species are numerous, 
and often represented by long series. An account of the butterflies by 
Miss Cora B. Sanders will shortly appear in the ‘‘ Annals and Magazine of 
Natural History” ; and it will then be seen that the evidence of change 
in certain forms is by no means wanting. 
+ ‘Science and the Faith,” London, 1889, pp. 174 e¢ seq. 
