Now all these difficulties are avoided if we admit that new forms of animal
life of all degrees of complexity appear from time to time with comparative
suddenness, being evolved according to laws in part depending on
surrounding conditions, in part internal--similar to the way in which
crystals (and, perhaps from recent researches, the lowest forms of life)
build themselves up according to the internal laws of their component
substance, and in harmony and correspondence with all environing influences
and conditions. [Page 144]

* * * * *

CHAPTER VII.

SPECIES AND SPACE.

The geographical distribution of animals presents difficulties.--These
not insurmountable in themselves; harmonize with other
difficulties.--Fresh-water fishes.--Forms common to Africa and India;
to Africa and South America; to China and Australia; to North America
and China; to New Zealand and South America; to South America and
Tasmania; to South America and Australia.--Pleurodont
lizards.--Insectivorous mammals.--Similarity of European and South
American frogs--Analogy between European salmon and fishes of New
Zealand, &c. An ancient Antarctic continent probable.--Other modes of
accounting for facts of distribution.--Independent origin of closely
similar forms.--Conclusion.

The study of the distribution of animals over the earth's surface presents
us with many facts having certain not unimportant bearings on the question
of specific origin. Amongst these are instances which, at least at first
sight, appear to conflict with the Darwinian theory of "Natural Selection."
It is not, however, here contended that such facts do by any means
constitute by themselves obstacles which cannot be got over. Indeed it
would be difficult to imagine any obstacles of the kind which could not be
surmounted by an indefinite number of terrestrial modifications of
surface--submergences and emergences--junctions and separations of
continents in all directions and combinations of any desired degree of
frequency. All this being supplemented by the intercalation of armies of
enemies, multitudes of ancestors of all kinds, and myriads of connecting
forms, whose _raison d'etre_ may be simply their utility or necessity {145}
for the support of the theory of "Natural Selection."

Nevertheless, when brought in merely to supplement and accentuate
considerations and arguments derived from other sourc