440 MR. H. B. GUPPY : PLANT-DISTRIBUTION 
that two years before the publication of his paper Huxley had outlined his 
views in two letters to Hooker, letters which are given in the 2nd edition 
of his * Life and Letters,’ by his son (ii. 465-6, 1903). 
Itis proposed to commenee this paper with a comparison of the views 
held by these investiga'ors respecting the early history of the distribution of 
the two families concerned. Both are agreed as to the original wide distri- 
bution of the primitive forms over the world, and both credit them with 
ignoring the great physical features of the globe, as at present displayed. 
Broad oceans, great deserts, and lofty mountain-ranges are all out of the 
reckoning in the respective discussions relating to the spread of these two 
families over the earth. Bentham holds to a very wide dispersion of the 
original stock of the Composite: over the world when the physical configura- 
tion was very different from what it is in our day. Huxley speaks of a 
* primitively continuous area of distribution," and leaves the matter there. 
With reference to the state of differentiation of the original stock when it 
conquered the earth, Bentham holds that the Old and the New Worlds 
possessed the family at the earliest recognizable stage. Huxley hypothecated 
a widely spread primitive type that subsequently differentiated over the 
globe. Both, in imputing a high antiquity to the respective stocks, know- 
ingly disregarded the lack of geological evidence, the one considering that 
the Composite dated back to an early geological period, the other holding 
that even the more specialized and consequently the more recent of the 
Gentians might have lived in the Cretaceous epoch. But Huxley went 
even beyond this when he assumed that the * Ur-Gentian" might be 
carried back “almost as much farther as probabilities permit us to carry 
the existence of flowering plants." 
For neither Bentham nor Huxley were the main features of the distri- 
bution of these two families concerned with means of dispersal. Huxley 
makes but little appeal to them and Bentham diseredits their efficacy. 
Bentham begins with a family already universally distributed, although he 
implies an original centre of dispersion. Huxley would have nothing to do 
with any such centres, and his plain words on this subject ought never to 
be forgotten by the student of distribution. All such notions were excluded 
for him in a type that followed the principle of the simpler and older the 
type the greater its range.—* The facts of distribution of the Gentianem 
are (he writes) not to be accounted for by migration from any centre of 
diffusion to which locality can be assigned in the present condition of the 
world." The problem was for him essentially a matter of the local 
modification of plants at different points of a *primitively continuous” 
area. Both Bentham and Huxley are at one in their conclusion that the 
main features of the distribution of these two families were determined 
in ages geologically remote ; and neither’s view of the early stages in the 
history of their distribution leaves any room for an appeal to centres of 
