206 SPENCER MOORE [SEPTEMBER 
and under its influence the seeds germinate; hereupon the temperature 
suddenly falls, and the young and tender seedlings are exposed, at a 
eritical period in their career, to entirely new and unfavourable con- 
ditions, and they perish accordingly. It is therefore no matter for 
wonder, and still less for drawing conclusions as to “aggressive power ” 
and “superiority” of the northern species, if introductions from the 
northern hemisphere are enabled to exist and multiply in the southern, 
while an embargo is placed upon southern species in Northern and 
Central Europe. Moreover, that this is the real reason why southern 
species are not domiciled with us seems clear when it is remembered 
how, in northern countries where the conditions are approximately 
similar to those obtaining in the southern hemisphere, southern intro- 
ductions are able to maintain themselves. One may cite, for example, 
the Western Mediterranean seaboard and the coast of Portugal, where 
a fair number of southern species—most of them, it is true, South 
African, from greater facility of intercourse—have succeeded in estab- 
lishing themselves, and apparently at some expense to the indigenous 
flora. 
There is one country north of the equator where Australian species 
readily become naturalised. Botanists who hold fast by the theory 
that the Australian flora is a mere geographical survival have been 
puzzled—as assuredly they ought to be puzzled—by the headway 
that species from Australia make when introduced into Southern 
India; nor does Mr. Wallace’s solution of the problem, ingenious 
though it be, at all relieve matters. Mr. Wallace cheerily avers that 
this fact is quite in harmony with the presumed predominance of 
northern forms. “For,” he says, “not only is the climate favourable, 
but the entire Indian peninsula has existed for untold ages as an 
island, and thus possesses the insular characteristics of a compara- 
tively poor and less developed flora and fauna as compared with the 
truly continental Malayan and Himalayan regions. Thus Australian 
plants can compete with a fair chance of success.”* But what 
evidence is there for Mr. Wallace’s idea? We venture to maintain, 
on the contrary, that the Indian flora is, in all essentials, a continental 
one, and, moreover, the “untold ages” Mr. Wallace alludes to are 
scarcely in point, for what we want is evidence as to the continued 
insularity, in a botanical sense, of a region which, for many thousands 
of years at least, has ceased to be an island. But why travel so far 
in search of an explanation when one is ready to hand? Why not 
admit that Australian species flourish in the Neilgherries simply 
because the present climate of that district is suitable to them? And 
why not go a step further, and allow that if a land connection existed 
between Australia and South India, and the intervening country 
enjoyed a climate like that of Australia, a considerable number of 
1 “Tsland Life,” p. 496, note. The fact there cited was communicated to Mr. Wallace 
by Sir Joseph Hooker. 
