BOTANICAL EVOLUTION. 371 
tribution were simply unanswerable. But when it was found that 
species were very intangible things, sometimes roughly detinable, 
sometimes perfectly undefinable,—when certain species were seen to 
arise almost before our eyes, as in the case of the varied breeds of 
pigeons, dogs, cattle, &e.—when, as in the horses of to-day, every 
stage in their recent development was unearthed in the Tertiary 
rocks of the Western States of North America—I say, when such 
facts as these became known to Science, the question of the geogra- 
phical distribution of organisms rose to an importance it had never 
before possessed. Let me, briefly, show by examples, some of the 
facts regarding the geographical distribution of our plants, and the 
suggested explanations of them. In going into this subject fully, I 
would require to treat it somewhat statistically, which, however 
satisfactory from a scientific point of view, would hardly prove to be 
a popular mode of exposition. I shall, therefore, confine my remarks 
to a few special cases. 
Our common Tutu (Coriaria ruscifolia) is familiar to every one 
who rambles on our Town Belt. Now this plant is only found in 
New Zealand and Chili. How are we to account for its occurrence in 
two such distant localities? Some would invoke gigantic geological 
changes to account for the fact, and suppose that it required vast 
ages for its accomplishment. But whatever explanation we give, it is 
quite clear that no simple statement will solve such a complex 
problem. The answer to the question would take a whole lecture to 
itself; and I must, therefore, refer any who are curious on the subject 
to Mr. A. R. Wallace’s “Island Life,” and other works, and Prof. 
Hutton’s papers on these subjects. 
Here is a still more familiar plant than the Tutu, viz., common 
Manuka (Leptospermum scoparium). If we eross to Victoria or 
Tasmania, we shall meet with the same plant in abundance. But 
alongside of this first species, we have a second (L. ericoides) almost 
as common, which is not found anywhere outside of New Zealand. 
I don’t know what the advocate of special creation would say as to 
the distribution of these two plants, but to the modern botanist’s 
mind the question at once arises—Did New Zealand get the Manuka 
from Australia, or did Australia get this one from New Zealand? I 
give you my own explanation, which you may accept or not as you 
please. Our largest-leaved species (also found in Australia) has very 
rigid leaves, with sharp points. Now such sharp-pointed leaves are 
probably so developed in order that they may be as obnoxious as 
possible to grazing animals. But there were no grazing animals in 
New Zealand—except, perhaps, Moas—until Europeans imported 
them, so that it is difficult to conceive why our plant should have 
developed such leaves. But when we remember that there are 
numerous indigenous grazing animals in Australia, and, further, that 
the genus Leptospermum is represented by some 20 species in 
Australia, and that it extends into the Indian Archipelago, it is 
surely the probable explanation that the genus has acquired its 
present characters outside of New Zealand, and that this species 
(ZL. scoparium) did not originate here, but was introduced at some 
unknown epoch, either from Australia, or from some regions lying to 
the North of Australia. But this answer will not solve the question 
of the occurrence of this second species in New Zealand alone. 
Well, again, I give you my own explanation. JL. ericoides is 
