at present, the study
of ancestral evolution introduces a new element of likeness and
unlikeness which is not only eminently deserving of recognition, but
must ultimately predominate over all others. A classification which
shall represent the process of ancestral evolution is, in fact, the
end which the labors of the philosophical taxonomist must keep in
view. But it is an end which cannot be attained until the progress of
palaeontology has given us far more insight than we yet possess, into
the historical facts of the case. Much of the speculative 'phylogeny,'
which abounds among my present contemporaries, reminds me very
forcibly of the speculative morphology, unchecked by a knowledge of
development, which was rife in my youth. As hypothesis, suggesting
inquiry in this or that direction, it is often extremely useful; but,
when the product of such speculation is placed on a level with those
generalisations of morphological truths which are represented by the
definitions of natural groups, it tends to confuse fancy with fact and
to create mere confusion. We are in danger of drifting into a new
'Natur-Philosophie' worse than the old, because there is less excuse
for it. Boyle did great service to science by his 'Sceptical Chemist,'
and I am inclined to think that, at the present day, a 'Sceptical
Biologist' might exert an equally beneficent influence.

[Sidenote: Physiology.]

Whoso wishes to gain a clear conception of the progress of physiology,
since 1837, will do well to compare Mueller's 'Physiology,' which
appeared in 1835, and Drapiez's edition of Richard's 'Nouveaux
Elements de Botanique,' published in 1837, with any of the present
handbooks of animals and vegetable physiology. Mueller's work was a
masterpiece, unsurpassed since the time of Haller, and Richard's book
enjoyed a great reputation at the time; but their successors transport
one into a new world. That which characterises the new physiology is
that it is permeated by, and indeed based upon, conceptions which,
though not wholly absent, are but dawning on the minds of the older
writers.

Modern physiology sets forth as its chief ends: Firstly, the
ascertainment of the facts and conditions of cell-life in general.
Secondly, in composite organisms, the analysis of the functions of
organs into those of the cells of which they are composed. Thirdly,
the explication of the processes by which this local cell-life is
directly, or indirectly, controlled and b