20 
JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
thousand years, it would suffice to keep up the existing number. But^ 
Nature is infinitely more prodigal of increase than that. Reproductive 
power is enormous, and necesarily there must be a constant war, uncom- 
promising though silent, between individuals of the same kind and 
between individuals of different kinds, between even the vegetable and 
animal life. You perhaps know the story of Clover, Bees, Mice and. 
Cats. The Clover must be fertilised by bees ; but mice destroy the combs- 
of the bees, and if the cats are too few to keep down the mice, bees 
cannot exist, and the Clover cannot produce seed. This is no exceptional 
case, and we cannot avoid seeing that nature is inextricably woven 
together. Some poets sing of peaceful nature — peace where there is no^ 
peace, where indeed the plant, the animal that cannot justify its existence 
by successful struggle, is doomed to extinction. Tennyson made no- 
mistake : he wrote that nature is " ever red with tooth and claw.'* The 
struggle for existence is exceedingly complex and affected by many^ 
circumstances ; but is it not clear that any variation possessing an advan- 
tage must tend to survive, while any variation or original not possessing^ 
the advantage must tend to die out ? Darwin's great principle of natural 
selection must always be at work. 
It has been well said that plants do not always grow where they 
would like to grow, but where they can grow. They are always, as it 
were, subjected to a tension of circumstances, and we have in this the 
explanation why it is that sometimes we can find artificial conditions 
that are better for plants than their natural conditions. You relieve the 
tension and the plants are benefited. That condition of things was 
exceedingly well shown by Sir William Dyer in the Gardeners' Chronicle 
a few years ago, and I do think that the highest skill of the gardener is 
often shown rather by his correct interpretation of what plants want 
than by his slavish reproduction of what they are accustomed to have. I 
recognise, of course, apart from this, that some conditions, necessarily 
artificial, forbid the application of other conditions that are perfectly 
natural and possible, or at least require their considerable modification. 
But this by the way. Bevenons a nos moutons. 
I come at last to the 
SUKVIVAL OF THE FiTTEST. 
If we admit variation, if we admit the struggle for existence — and' 
surely we do — we must admit, I think, the survival of the fittest. We 
may look at it in a very simple way. By variation some plants are 
certain to be more fit, or less fit, than the parent, and some may possess 
a distinct advantage. The struggle for existence is neither more nor less 
than a sifting process — I wish to refer to it again as a sifting process — 
and it is a truism to say that the survivors of the process must be the 
fittest to survive. The survivors must be those that are too large, too 
fit, to go through the sieve. It is unnecessary to develop further illus- 
tration, and I will only refer you to Darwin's graphic conclusion of the 
fourth chapter of his " Origin." As with a tree, so it is, he says, with 
the Tree of Life. The green and budding twigs are existing species. 
Many of the twigs that the tree had in a younger state have succumbed 
in the struggle of the tree within itself. Of the branches that the tree 
