as common water was found to be an infusion of them. In the eighteenth
century naturalists were very keen on the Infusorian Amoebas, and were
much struck by the way in which the members of this old family behaved
and developed. But it was still possible for Linnaeus to begin a
treatise by saying 'There are just so many species as there were forms
created in the beginning,' though there were hundreds of commonplace
Scotch gardeners, pigeon fanciers, and stock breeders then living who
knew better. Linnaeus himself knew better before he died. In the
last edition of his System of Nature, he began to wonder whether the
transmutation of species by variation might not be possible. Then came
the great poet who jumped over the facts to the conclusion. Goethe said
that all the shapes of creation were cousins; that there must be some
common stock from which all the species had sprung; that it was the
environment of air that had produced the eagle, of water the seal, and
of earth the mole. He could not say how this happened; but he divined
that it did happen. Erasmus Darwin, the grandfather of Charles, carried
the environment theory much further, pointing out instance after
instance of modifications made in species apparently to adapt it to
circumstances and environment: for instance, that the brilliant colors
of the leopard, which make it so conspicuous in Regent's Park, conceal
it in a tropical jungle. Finally he wrote, as his declaration of faith,
'The world has been evolved, not created: it has arisen little by little
from a small beginning, and has increased through the activity of the
elemental forces embodied in itself, and so has rather grown than come
into being at an almighty word. What a sublime idea of the infinite
might of the great Architect, the Cause of all causes, the Father of all
fathers, the Ens Entium! For if we would compare the Infinite, it would
surely require a greater Infinite to cause the causes of effects than to
produce the effects themselves.' In this, published in the year 1794,
you have nineteenth-century Evolution precisely defined. And Erasmus