82 Recently published Ornithological Works. 
written “a single syllable antagonistic to Darwin's Theory 
of Natural Selection/' we are not at all sure that those 
who have read his interesting essay will be able to acquit 
him of having committed this indiscretion. It is quite certain 
that Isolation—the prime factor, according to Mr. Dixon— 
plays a great part in the modification of species; for without 
isolation, as Mr. Dixon himself very clearly shows, the mem¬ 
bers of a species can breed freely together, and little or no 
variation will be produced. But surely neither Darwin nor 
his disciples have ever ignored the force of this element in 
the variation of species. Isolation, no doubt, plays a most 
important part in the preservation of differences when they 
have arisen. Mr. Dixon has not told us how isolation can 
make differences. Climatic Influence, of which Mr. Dixon 
speaks in his second chapter, is, in many cases, an impor¬ 
tant factor in their production; but where this does not 
come into play, as is often the case, we cannot understand 
how Mr. Dixon proposes to get on without Natural Selection; 
and even when climatic influence is manifestly an impelling 
cause of variation, “ Natural Selection" may be a concomi¬ 
tant factor. While thanking him, therefore, for his essay, 
we still think that he has failed to show that we can get 
on “ without the aid of the Darwinian Hypothesis." 
9. W. Evans on some Scottish Birds . 
[Notes on the Birds of the Island of Eigg. Pr. R. Phys. Soc. Edinb. 
1885, pp. 430-448. 
Note on the Breeding of the Marsh-Tit (Porus palustris) in Stirling¬ 
shire during 1884. Tom. cit. pp. 448-451.] 
Lest any of our readers should be so ignorant of Scottish 
geography as not to know the precise position of Eigg, we 
may make a concession, and state that it lies about halfway 
between the island of Bum and that portion of the mainland 
where Inverness-shire (to which it belongs) marches with 
Argyll. On Eigg Mr. Evans passed about five days, and 
from his own observations, largely supplemented by notes from 
journals kept by Messrs. J. J. Dalgleish, A. C. Stark, A. F. 
