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FRÓM THE STANDPOINT OF AN IDEALIST. 471 
TABLE X. 
The distribution of the 272 Families of the Angiosperms in the North and 
South Hemispheres. 
(The data in Table IIT. have here been utilised. The tropics include 
the sub-tropies, and all other regions are classed as temperate.) 
1 ae? 
| 
North Temperate in varying degree ........ | 122 or 45°/, 
Tropical Sip DR aid p 220 or 81 9/5 
South Temperate  ,, bs ROREM 116 or 45 9/, 
Norr.—The total number of families represented to a greater or less extent in temperate 
regions, that is in regions outside the tropies or subtropics, is 152 or 56 per cent. The 
representation in the tropics is above shown to be 220 or 81 per cent. 
SUMMARY. 
From a consideration of the problems of plant-distribution, the writer is 
led to regard the history of the Angiosperms as resolving itself into two 
principal eras :— 
(1) The era that witnessed the rise of the great families, a period of 
relatively uniform conditions. 
(2) The era that witnessed the differentiation of these family types in 
response to the differentiation of the climatic and other conditions. 
It is argued that conclusions drawn from the prevailing influences now in 
operation could only be applied to the differentiation of the ancient family 
types—that is to say, to the second era in plant-history. It is not possible, 
so it is held, to apply a theory based on the present to an age of other things, 
other ways, and other conditions. Only the hypothesis that finds its guide 
to the past in the abnormalities of the present can be of service to us in the 
interpretation of times so different. 
The subject is introduced by a reference to two papers, contributed to the 
*Journal of the Linnean Society, which have an important bearing on 
the subject, the one by Bentham on the Composite, the other by Huxley 
on the Gentians. Then follows a statement of the differentiation hypothesis 
which involves the differentiation of primitive world-ranging types in response 
to the progressive differentiation of their originally uniform conditions. Allu- 
sion is then made to the dilemma into which all theorists fall when they come 
to handle the larger groups, the very persistence of whieh in our own age 
depends on the stability of their essential characters. If stable now, why so 
unstable then? We are thus forced to the conclusion that in the distant era 
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