15o HERBERT SPENCER

their lowest members is just the kinship which the
hypothesis of evolution implies." " Even in the
absence of these specific agreements, the broad fact
of unity amid multiformity, which organisms so
strikingly display, is strongly suggestive of evolution.
Freeing ourselves from pre-conceptions, we shall see
good reason to think with Mr Darwin, " that pro-
pinquity of descent—the only known cause of the
similarity of organic beings—is the bond, hidden as it
is by various degrees of modification, which is partly
revealed to us by our classifications " (Principles of
Biology, Rev. Ed. vol. L p. 448).

II. Arguments from Embryology. Organisms may
be arranged on a tree which symbolises their
structural affinities and divergences. On the evolu-
tionist interpretation this is an adumbration of the
actual genealogical tree or Stammbaum. But when we
consider the facts of embryology we find that the
developing organism advances from stage to stage by
steps which are more or less comparable to the various
levels and branchings of the classificatory tree. There
is a resemblance, sometimes a parallelism, between
individual development and the grades of organisation
which have or have had persistent stability as living
creatures. " On the hypothesis of evolution this
parallelism has a meaning—indicates that primordial
kinship of all organisms, and that progressive
differentiation of them which the hypothesis alleges.
On any other hypothesis the parallelism is meaning-
less." It is true that there are nonconformities to
the general law that individual development tends
to recapitulate racial history, or that ontogeny tends
to recapitulate phytogeny. There may be in theel mixture of scientific and trans-s intrinsic incoherence; worthless as