JOHN MACOUN ON CANADIAN POLYPETALA. 153 
It is very probable, however, that the former will be detected in Ontario or Quebec as 
it has been found in Maine. 
The Rocky Mountains seem to be the eastern limit of many western species, but present 
no barrier to the eastern, as nearly all the species that reach the eastern base appear again 
on the west side. The Coast Range, however, is the true boundary of the eastern species, 
and many disappear on its eastern slopes. West Coast plants, when found in the interior, 
are mountain species of which many examples are known amongst the Saxifragaceæ. An 
examination of mountain and coast species leads me to think that the hygrometric condition 
of the atmosphere has much to do with the distribution of such species, and that the species 
comprising the mountain flora generally prefer, if they do not require, an atmosphere almost 
constantly at the point of saturation. Mountain or northern species seem as much at home 
in a peat bog in a low latitude as they are in their native habitats, and the cause is not far 
to seek. Such bogs are cool all summer, and the air over the bog close to the surface is at 
the dew-point nearly all the time. Southern species, though natives of a swamp, should be 
looked for on warm sandy tracts, as they there meet with the continuous heat that they seem 
to require. The one finds in the cold water of the bog compensation for the want of 
moisture in the air, while the other, imbibing less moisture, seems to need less heat, and 
both, in their changed condition, live in the same locality, thrive and ripen their seeds 
year after year. 
In studying the present aspect of our flora, one is irresistibly led to look at the past, 
and although I am not prepared to speak dogmatically of it, yet, with the aid of other 
workers, I may be able to throw some light on the subject. The problem is one that I 
approach with diffidence, as many able men have already given their views on the subject, 
and my investigations may lead me to differ from them. After carefully examining all the 
available writings on the subject of the origin and dispersal of species, I am strongly 
impressed with the conviction that our present flora originated at the north, and not it 
alone but all floras of which we haye any record in the rocks. This view was adopted toa 
certain extent by our esteemed president nearly four years ago, in his able article on “ The 
Genesis and Migrations of Plants.” Asa Gray, who, of all living botanists, knows most in 
regard to the distribution of species on the American continent, in an article written in 1878, 
says :—‘‘ Long genealogies deal more or less in conjecture; but we appear to be within 
the limits of scientific inference when we announce that our existing temperate trees came 
from the north, and within the bounds of high probability when we claim not a few of 
them as the originals of present species.” My reasons for adopting this view in a more 
extended sense I will give in a few words. 
1. Darwin in his work on “ The Origin of Species,” propounds the doctrine of Natural 
Selection, and in discussing it, seems to state that anything and everything that tends to de- 
velop, restrict, weaken or strengthen a species belongs to his theory, and he brings to his 
assistance another doctrine—the Survival of the Fittest, which I interpret to mean the sur- 
vival of the strongest, that is, those endowed with the greatest vitality. Now, it is a well 
understood law that all plants become more prolific as they approach the northern confines 
of their restricted area, and as they approach their southern limit they produce little else but 
leaves. Numerous examples could be adduced to establish this from both kingdoms of 
nature. In the north, therefore, we have vigor and the power of reproduction, while in 
Sec. IV., 1883. 20 
