FROM THE STANDPOINT OF AN IDEALIST. 447 
species and ending with the family, then we shall make an important step 
towards the proper appreciation of the main problems concerned in dis- 
tribution. That two such opposite methods should seem possible, as 
beginning in one case with the species and the other with the family, 
and that we should be indifferent to the result, whether it be chaos or 
order, are indications of failure to appreciate what really matters in plant- 
distribution. 
It is by no means urgent to go back to the beginning of things, to account 
for the origin of families or even of species, to seek for centres of dispersion 
or the homes of plant-groups, to upset the world’s geography, or to account 
for progressive evolution. What is urgent is to be able to state the main 
problem, and that cannot be done without some agreement about essentials. 
One cannot help thinking that if a hundred students of distribution were 
asked to do this, they would view the subject from such a variety of 
standpoints that the task of finding a common basis of agreement would 
be exceedingly difficult. The claim of the family for priority of treatment, 
which is supported in this paper, is founded on what Bentham terms in the 
case of the Composite the permanence of its characters. The very per- 
sistence of the family lies in the fact that these characters make little or no 
response to the extreme variations of existing conditions ; and it is with the 
object of emphasizing its suitability for serving as a common ground of 
agreement that these pages have been written. 
The response of the families to the bi-cleavage of the land-mass of the 
globe.—1lt is a remarkable fact that whilst the families of the Angiosperms 
. respond in a marked degree to the differentiation of the climatic zones, they 
largely ignore the cleavage of the land into two great masses diverging from 
the north. Of the 272 families recognized in Engler's system 192, or 
70:5 per cent., occur in both the eastern and western hemispheres (Tables I., 
IL, IIL). It would almost appear, as far as their occurrence in both 
hemispheres is concerned, that the general distribution of the families over 
the globe would not have been very different if all the land had been one 
continuous little-divided mass. 
It may, however, be objected that this community of families between the 
Old and the New World may be mainly restricted to those most at home in 
the colder latitudes of the north where the American and Eurasian land- 
masses approach each other. If this were so, there would be but little force 
in the above contention that the family largely ignores the bi-cleavage of the 
land. Buta glance at the columns of Table IIT. will convince one that this 
behaviour of the family is just as characteristic of the warm equatorial 
regions as it is of the colder northern regions. There are 120 families 
restricted to tropical and sub-tropical latitudes. Of these 73, or 61 per cent., 
are found in both the eastern and western worlds. There are 52 families 
that are only at home in extra-tropical regions. After removing those 
confined to the southern hemisphere, there remain 36, of which 23, or 64 per 
CR Pop sd eee, ae 
