e no cognisance of the increasing
complexity of the embryo, of the separating-out of tissues, of the
moulding of organs, of the harmonious adaptation and adjustment of the
parts to form a working whole.

In general, the fault of the atomists is that they do not respect the
limits which Nature herself has prescribed to the process of logical
analysis and disintegration of the organism; they do not recognise the
existence of natural and rational units or unities; they forget the one
great principle of rational analysis, "that, by universally valid,
inductive, logical method, natural objects must in all cases be accepted
and dealt with in the combination and concatenation in which they are
given" (p. 10).

The atomists at least recognised one natural organic element, the cell;
the materialistic physiologists of the time resolved even this unity
into an aggregate of inorganic compounds, and regarded the organism
itself as nothing but a vastly complicated physico-chemical mechanism.
From this point of view morphology had no right of existence, and we
find Ludwig, one of the foremost of the materialistic school,
maintaining that morphology was of no scientific importance, that it was
nothing more than an artistic game, interesting enough, but completely
superseded and robbed of all value by the advance of materialistic
physiology.[298]

Naturally enough, morphologists did not accept this rather contemptuous
estimate of their science, but held firmly to the morphological
attitude. So Leuckart in his reply to Ludwig, so Rathke in a letter to
Leuckart published in that reply, so Reichert in his _Bericht_, so J. V.
Carus in his _System der thierischen Morphologie_,[299] upheld the
validity, the independence, of morphological methods. Leuckart and
Rathke called attention to the absolute impossibility of explaining by
materialistic physiology the unity of plan underlying the diversity of
animal form. J. V. Carus, who was convinced of the validity of
physiological methods within their proper sphere, drew a sharp
distinction between systematics and morphology on the one hand, and
physiology on the other. Physiology had nothing to do with the problems
of form at all; its business was to study the physical and chemical
processes which lay at the base of all vital activities. Morphology, on
its part, had to accept form as something given, and to study the
abstract relations of forms to one another. "On this point," he writes,
"stres