Facts and Arguments for Darwin | Page 2

before us. Moreover, it is but fair to
leave it to Darwin himself at first to beat off the attacks of his
opponents from the splendid structure which he has raised with such a
master-hand.
F.M.
DESTERRO, 7TH SEPTEMBER, 1863.

CONTENTS.
CHAPTER 1.
INTRODUCTORY.
CHAPTER 2.
THE SPECIES OF MELITA.
CHAPTER 3.
MORPHOLOGY OF CRUSTACEA.
CHAPTER 4.
SEXUAL PECULIARITIES AND DIMORPHISM.
CHAPTER 5.
RESPIRATION IN LAND CRABS.

CHAPTER 6.
STRUCTURE OF THE HEART IN EDRIOPHTHALMA.
CHAPTER 7.
DEVELOPMENTAL HISTORY OF PODOPHTHALMA.
CHAPTER 8.
DEVELOPMENTAL HISTORY OF EDRIOPHTHALMA.
CHAPTER 9.
DEVELOPMENTAL HISTORY OF ENTOMOSTRACA,
CIRRIPEDES, AND RHIZOCEPHALA.
CHAPTER 10.
ON THE PRINCIPLES OF CLASSIFICATION.
CHAPTER 11.
ON THE PROGRESS OF EVOLUTION.
CHAPTER 12.
PROGRESS OF EVOLUTION IN CRUSTACEA.

HISTORY OF CRUSTACEA.
CHAPTER 1.
INTRODUCTORY.
When I had read Charles Darwin's book 'On the Origin of Species,' it

seemed to me that there was one mode, and that perhaps the most
certain, of testing the correctness of the views developed in it, namely,
to attempt apply them as specially as possible to some particular group
of animals. such an attempt to establish a genealogical tree, whether for
the families of a class, the genera of a large family, or for the species of
an extensive genus, and to produce pictures as complete and intelligible
as possible of the common ancestors of the various smaller and larger
circles, might furnish a result in three different ways.
1. In the first place, Darwin's suppositions when thus applied might
lead to irreconcilable and contradictory conclusions, from which the
erroneousness of the suppositions might be inferred. If Darwin's
opinions are false, it was to be expected that contradictions would
accompany their detailed application at every step, and that these, by
their cumulative force, would entirely destroy the suppositions from
which they proceeded, even though the deductions derived from each
particular case might possess little of the unconditional nature of
mathematical proof.
2. Secondly, the attempt might be successful to a greater or less extent.
If it was possible upon the foundation and with the aid of the
Darwinian theory, to show in what sequence the various smaller and
larger circles had separated from the common fundamental form and
from each other, in what sequence they had acquired the peculiarities
which now characterise them, and what transformations they had
undergone in the lapse of ages,--if the establishment of such a
genealogical tree, of a primitive history of the group under
consideration, free from internal contradictions, was possible,--then this
conception, the more completely it took up all the species within itself,
and the more deeply it enabled us to descend into the details of their
structure, must in the same proportion bear in itself the warrant of its
truth, and the more convincingly prove that the foundation upon which
it is built is no loose sand, and that it is more than merely "an
intellectual dream."
3. In the third place, however, it was possible, and this could not but
appear, prima facie, the most probable case, that the attempt might be

frustrated by the difficulties standing in its way, without settling the
question, either way, in a perfectly satisfactory manner. But if it were
only possible in this way to arrive for oneself at a moderately certain
independent judgment upon a matter affecting the highest questions so
deeply, even this alone could not but be esteemed a great gain.
Having determined to make the attempt, I had in the first place to
decide upon some particular class. The choice was necessarily limited
to those the chief forms of which were easily to be obtained alive in
some abundance. The Crabs and Macrurous Crustacea, the Stomapoda,
the Diastylidae, the Amphipoda and Isopoda, the Ostracoda and
Daphnidae, the Copepoda and Parasita, the Cirripedes and
Rhizocephala of our coast, representing the class of Crustacea with the
deficiency only of the Phyllopoda and Xiphosura, furnished a long and
varied, and at the same time intimately connected series, such as was at
my command in no other class. But even independently of this
circumstance the selection of the Crustacea could hardly have been
doubtful. Nowhere else, as has already been indicated by various
writers, is the temptation stronger to give to the expressions
"relationship, production from a common fundamental form," and the
like, more than a mere figurative signification, than in the case of the
lower Crustacea. Among the parasitic Crustacea, especially, everybody
has long been accustomed to speak, in a manner scarcely admitting of a
figurative meaning, of their arrest of development by parasitism, as if
the transformation of species were a matter of course. It would
certainly never appear to any one to be a pastime worthy of the Deity,
to amuse himself with the contrivance of these marvellous cripplings,
and so they were supposed to have fallen by their own