The statements of this distinguished anatomist had been far from giving the same
satisfaction to naturalists in general that they had done to the commission of the Academy.
Their importance, however, had not been overrated; as, should they prove to be founded in
truth, they would have an influence much beyond the dismemberment of a small order of
Mollusks, or the establishment of one or two new families. Naturalists had hitherto placed
great confidence on deductions drawn from analogy and the correlation of parts. Their
experience had shown them that the works of nature exhibited such an uniformity of design
as enabled them, from the existence of certain characters, to infer the existence of others with
which they, had been found to be uniformly associated. Upon such a faith in the constancy
of nature, most generalisations are founded. The discoveries of M. de Quatrefages tended to
shake this confidence, and to vitiate in future all arguments drawn from analogy. .It was not
to be wondered at, therefore, that his statements were received with mistrust, and the supposed
facts submitted to a rigorous scrutiny.
Among the foremost to oppose these views was M. Souleyet. In a communication to the
Academy of Sciences,* this naturalist expresses his conviction, founded upon a careful
anatomical investigation, that the so called gastro-vascular apparatus was no other than a
system of highly developed biliary ducts, rendered necessary by the dismemberment of the
liver in these animals. Rejecting, therefore, the idea of the union of functions assigned to
them, he proposed to call these vessels gastroTbiliary. He demonstrated, from the anatomy of
Eolis, between which genus and Eolidina he could see no essential difference, that the marginal
canal, described by M. de Quatrefages, and considered by him analogous to that of the
Medusae, did not exist, and further asserted that in Eolis the vascular system was not less
perfect than in the other Mollusca. No degradation from the usual type of the class was
therefore to be found in the animals examined.
In a Report to the British-Association for the Advancement of Science, in 1844, we again
objected to most of the opinions of M. de Quatrefages on this subject. And in the first part
of a paper on the anatomy of Eolis,f published in 1845, Mr. Hancock and Dr. Embleton
pointed out several errors of detail in that gentleman’s memoirs. They there take the same
view of the gastro-vascular system as that expressed by M. Souleyet.
Subsequently, M. de Quatrefages entered into a general exposition of his views on the
organisation and arrangement of the animal kingdom, showing that with these his observations
on the anatomy of the Mollusca perfectly agreed. In conformity with the views of Professor
Milne Edwards, he contends for a plurality of series in the animal kingdom, and the degradation
of many of them; and he further states that, in numerous instances, the general form of the
body and the internal organisation are perfectly independent of each other.. Phlebenterism,
he says, is not confined to the Mollusca: “ It exists in the animal kingdom taken as a whole,
and in many of the secondary and tertiary series which concur to form it. Nearly throughout,
we see it coincide with the manifest degradation of the entire organisation. Almost always
it coincides with the simplification or complete annihilation of the organs of circulation. ”J
The observations of M. Souleyet, in reply to those of M. de Quatrefages, were; for the most
part, directed to the two principal points in dispute; namely,—the function of the branched
* ‘ Comptes Rendus/ v. 19, p. 355 (1844).
% 1 Comptes Rendus/ v. 19, p. 809.
t ‘Ann. Nat. Hist./ y. 15, pp. 1, 77.
apparatus of the stomach, and the presence or absence of veins in the circulatory system. It
is unnecessary here to mention in detail the whole of the papers communicated to the Academy,
or published in the French journals in connexion with this controversy, which was carried on
for some time with considerable energy. We may state, however, that M. de Quatrefages
admitted the existence of some errors in his earlier papers, and was willing to give up the
PMebenteraia as a separate order, but still maintained the correctness of his views on the
gastro-vascular system and the degradation of types. He proposed to retain the term
Phlebenterism, in a more extended signification, to designate that species of degradation which
consists in the union of different functions in one system of vessels, to be found, according to
his views, in all divisions of the animal kingdom.
We may perceive in the desire to discover proofs of this theory the source of most of the
errors with respect to facts which we cannot doubt that M. de Quatrefages has committed in
his Memoir on the Phkbenterata. Since its publication we have discovered on the English
coasts undoubted examples of most of the genera there described, and we have been able to
demonstrate* that no degradation of type, to the extent that he describes, is to be found in any
of them. In every case we found a heart and blood-vessels more or less complete, and the
anal opening was present in all. So far as regards these points, therefore, we may dismiss as
purely imaginary the extreme degradation of type which some of these little animals were
supposed to exhibit.
The matter in dispute was ultimately referred to a new commission of the Academy of
Sciences, whose report, drawn up by M. Isadore Geoffroy Saint Hilaire, was presented to the
Academy on the 13th of January, I8 5 l.f The commission, after considering attentively the
evidence submitted 'to them by the contending parties, came to the resolution, that the
existence of a heart, arteries, and branchio-cardiac vessels in the Phlebenterate Mollusca is
proved, and that a regular circulation does exist, but that whether it is completed by a system
of veins or by means of lacunes is still open to dispute. With respect to the functions of the
branched vessels called gastro-vascular, the commission think that further evidence is
desirable, but from the existence of a system of vessels specially appropriated to the circulation,
as well as of organs performing (at least in part,) the office of respiration, they think that the
threefold office assigned to them by M’. de Quatrefages can scarcely be maintained.
Meanwhile, M. de Quatrefages brought the subject before the Biological Society of Paris,
and a commission of that Society was likewise appointed for its investigation. After a careful
examination of the subject, they agreed to a report which was drawn up by Dr. Charles
R o b in T h i s able report, which is extremely elaborate, filling a pamphlet of 132 closely
printed pages, appeared very nearly at the same time with that of the Academy. On the two
main points in dispute the commission came to the conclusion that M. Souleyet is correct, and
dismiss the idea of Phlebenterism as untenable. They consider the ramifications of the
digestive system to be true biliary ducts in connexion with a divided liver, and that they do
not fulfil any other function than the usual one of that organ. They, moreover, consider that
the circulatory system in these animals {Eolis, Actceon, &c.) is complete, the so-called lacunes
being similar to the blood-sinuses known to exist in particular cases throughout all departments
* ‘Ann. Nat. Hist./ v. 13, p. 161 ; v. 18, p. 289 ; and 2d series, v. 1, p. 101.
t ‘ Comptes Rendus Hebdomadaires/ v. 32, p. 33.
% ‘ Rapport à la Société de Biologie,’ &c., par M. le Dr. Charles Robin. Pails, 1851.
2