Mh. H. B. GUPPY ON PLANT-DISTRIBUTION. 439 
Plant-Distribution from the Standpoint of an Idealist. 
By H. B. Guepy, M.B: F.L.S. 
[Read 7th February, 1918. ] 
THE most interesting and at the same time the most mysterious features of 
plant-distribution centre around the rise of the great families. These ancient 
plant-groups belong so much to an era of other things, other ways, and other 
conditions, that the employment of such terms as * genera” and “ species " 
in connection with their origin seems to be almost meaningless. All the 
influences that we see normally at work around us now could only relate to 
the differentiation of the family-types into genera and species ; and any 
theory that on such grounds endeavours to apply the present to the past in 
deciphering their origin would apparently be attempting an impossible task. 
One ventures to think that only the hypothesis that finds its guide to the 
past in the abnormalities of the present could be of service here. This would 
seem to place the pre-differentiation era, the age that witnessed the rise of 
the great families, outside the field of the Natural Selection theory, and in 
default of its aid to cause us to look to the Mutation hypothesis for guidance. 
Yet, although Darwin came to reject the “sport,” the original scope of his 
theory was large enough to admit it; and it may be,as the writer holds, 
that the antithesis between the two theories is more apparent than real. Yet 
the Mutation hypothesis was conceived in the spirit of Darwinism, was 
framed on Darwinian lines, and was formulated in Darwinian language ; 
` and it is not easy to understand how the two theories were allowed to 
acquire the appearance of being mutually exclusive. There is room for both 
within the boundaries of the theory of Natural Selection as Darwin first 
conceived it; and there is work for both schools in its extension, its improve- 
ment, and its emendation. Whilst the Mutationist would find a fruitful 
feld for his labours in the era of the rise of the great family-types, the 
Darwinian evolutionist would be occupied with their subsequent differentia- 
tion into tribes, genera, and species. 
The rise of the great families and the lesson of the Composite and the 
Gentians.—Two papers of great importance from this standpoint to the 
student of plant-distribution were published in the * Journal of the Linnean 
Society’ in 1873 and 1888, the first by Bentham on the Composite, the 
second by Huxley on the Gentians. They are important because, in dealing 
with the beginnings of the distribution of these two families, they ask the 
same questions and raise the same issues; and it is needless to add that, 
although in one case the methods employed were those of a great botanist 
and in the other those of a great zoologist, they bear in each case the 
impress of a master hand. Those interested in the subject will remember 
