SEPTEMBER 10, 1897.] 
of Phytonomus punctatus, of Porthetria dispar, 
of Anthonomus grandis, of Icerya purchasi 
and many others may probably be princi- 
pally laid to this cause. 
I should be remiss did I not refer to an- 
other aspect of the accidental introduction 
of species, viz, that it not only adds 
species to a native fauna, but also that it 
often causes the disappearance of native 
forms. Since the establishment, within our 
boundaries, of Pieris rape, our native Pontia 
oleracea has almost entirely disappeared in 
localities in which it formerly abounded, 
and in some sections has entirely disap- 
peared. Since Doryphora 10-lineata came 
east and multiplied upon the cultivated 
potato in such prodigions numbers, the 
formerly common eastern Doryphora juncta 
has become a rare species. Walsh pointed 
out 30 years ago that one effect of the 
westward spread of the European Mytilaspis 
pomorum was to cause the gradual local dis- 
' appearance of the native Chionaspis furfurus. 
Hubbard has shown that the increase of 
the imported Mytilaspis citricola in Florida 
was followed by the decrease of Mytilaspis 
gloverti, which, though not native, was an 
earlier importation—a most interesting, 
and, so far as records go, unique case. In- 
stances might be multiplied which will 
show that the establishment of foreign 
species thus often produces at least a dual 
effect on the character of the fauna as a 
whole. 
Tn closing, it will not be inappropriate to. 
point out that the accidental importation 
of species is only one of the ways in which 
the agency of man is altering the character 
of native faunas, and that, in spite of its 
extent, it is really the least of the ways. 
The influence of civilization is immediately 
destructive to natural floras and faunas. 
It is already too late to gain an adequate 
idea of natural conditions in even recently 
settled portions of the globe. Wallace has 
dwelt upon the comparatively scanty and 
SCLENCE. 397 
unimportant results to natural history of 
most of the great scientific voyages of the 
various civilized governments during the 
present century, from which it has resulted 
“that the productions of some of the most 
frequently visited and most interesting 
islands on the globe are still very imper- 
fectly known, while their native plants and 
animals are being yearly exterminated. 
* * * Such are the Sandwich Islands, 
Tahiti, the Marquesas, the Phillippine 
Islands and a host of smaller ones; while 
Bourbon and Mauritius, St. Helena and 
several others have only been adequately 
explored after an important portion of 
their productions has been destroyed by 
cultivation or the reckless introduction of 
goats and pigs.” (‘Island Life,’ p. 7.) 
Elsewhere he shows that the introduction 
of goats into St. Helena utterly destroyed a 
whole flora of forest trees, and with them 
all the insects, mollusca, and perhaps birds 
dependent upon them. And further, that 
“cattle will, in many districts, wholly pre- 
vent the growth of trees ; and with the trees 
the numerous insects dependent on those 
trees, and the birds which feed upon the 
insects, must disappear as well as the small 
mammalia which feed on the fruits, seeds, 
leaves or roots.”? Many local American in- 
stances have been brought together by Mr. 
EF. M. Webster in an important paper 
entitled ‘ Biological effects of civilization on 
the insect fauna of Ohio,’ which comes to me 
as I write these closing lines. 
But the purpose of this address has been 
to dwell solely upon the question of the 
spread of species, and I must not touch upon 
other topics, however closely akin. It 
seems to me that the practical point to 
which we must come, after summarizing all 
that has been shown, is that since so many 
species have beenimported by pure accident, 
and have succeeded perfectly in becoming 
acclimatized, may not much be accomplished 
by wisely planned and carefully guarded 
