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rivers in incredible numbers, overcoming all obstacles, ascending vertical walls or flood-gates,
entering every larger and swollen tributary, and making their way even over terra firma to waters
shut off from all communication with rivers. Such emigrations have long been known by the
name l Eel-fairs? The majority of the Eels which migrate to the sea appear to return to fresh
water, but not in a body, but irregularly, and throughout the warmer part of the year. No
naturalist has ever observed these fishes in the act of spawning, or found mature ova; and the
organs of reproduction in individuals caught in fresh water are so little developed and so much
alike, that the female organ can be distinguished from the male only with the aid of a microscope."

MIGRATIONS OF EELS. In attempting to review this subject I am sure I cannot do better
than to translate at length a communication just received from my friend Dr. Berthold Benecke,
professor in the University of Konigsberg :

"The coloration of Eels varies greatly not only in diiferent localities, but in the very same
places: the back may be dark blue or greenish black; the sides, lighter blue or green ; the belly,
white; sometimes the back is only slightly darker than the sides; sometimes there are olive-green
individuals with a golden-yellow band upon their back, sometimes they are entirely golden-yellow,
and, very rarely, entirely white. The Eel lives in deep, quiet waters with muddy bottom; it
burrows out holes and tunnels in which it rests quietly during the day, while at night it comes
out in search of food. From the deck of a steamer passing througli rivers or canals one may see
upon the banks, which are laid bare by the waves produced by the motion of the vessels, numerous
Eels with half of their bodies projecting from their lurking holes.

"The Eel feeds upon all kinds of small water animals, and may be found on the spawning
places of other flsh in great troops, going there for the purpose of feeding upon the eggs. They
feed also upon crabs at the period when they are shedding their shells, and have in many localities
in Germany completely exterminated them. Since the Eel is everywhere known as a greedy
robber, many accounts have been given of their wanderings, in which they have made their way
into the pea-patches to feed upon pease. The oldest reference of this kind is that of Albertus
Magnus, who remarks in his book of animals, published at Fraukfort-on-the-Main in 1545 : ' The Eel
also comes out of the water in the night-time into the fields, where he can find pease, beans, or lentils.'
This statement was contradicted in 1666 by Baldner, 1 who writes concerning the Eel: 'They eat
fish, do not come on the land, and do not eat pease, but remain in the water always, and are
nocturnal animals.'

" Forthwith, new statements were made which tended to show the actuality of the wanderings
of the Eels in the pea-patches. For instance, Bach, in his ' Natural History of East and West Prus-
sia,' published in 1784, maintained that Eels frequently were caught in the pea-patches in the
vicinity of the water, where they fed upon the leaves, or, according to other accounts, upon the
pease themselves, and continues : ' These movements explain the paradoxical fact that in Prussia
and Pomerania fish have been caught upon dry land by the use of the plow, for the peasants,
in warm nights when the Eels are in search of the pease, towards morning when it is not yet day
make furrows with the plow between them and the water, and these are the nets in which the

'Eecht natUrlicho Beschreibung und Abmahluog <ler Wosser-Vogel, Fischen, vierfiissigen Thier, Insecteu und
Gewirm, so bey Strassburg in den Wassern siud, die ich solber geschossen nnd die Fisch gefangen, aucn alles in meiner
Hand gehabt. Leonhard Baldner, Fischer und Ilagineister in Strassburg gefertigt worden 1666. Manuscript. (Cited
by von Siebold, "SUsswasserfische von Mitteleuropa," Leipzig, 1863.)


Eds arc caught. Sim-!- the Kel moves with ease only upon the grass, its return to the water is cut
utl'ln tin- soil which lias liccn thrown up. The peasants consider it as a sign of approaching
stormy weather when the Eels come out of the water upon dry land."

A person u rites to me from Lyck : 'In storms they coine out into the pea-patches, and at this
tiint' people spread sand or ashes around, and thus prevent their return.' Such tales are even now
numerous in the newspapers.

"The small si/.e of the gill-opening makes it possible for the Eel to live for a long time out of the
water, and it is possible that in their wanderings over moist meadows they may find places in which
there are snails and other desirable food. The explanation of their supposed wanderings over the
pea patches is, that the Eels, which have been found at different times in the fields or meadows,
have been lost by poachers, who threw them away in their flight. Many times dead Eels have
been found upon meadows over which they have swam, the meadows being flooded, and, in spite
of the nearness of the water, have afterwards been unable to return to it.

"Although the activity and tendency among the young Eels to wander is very great, yet we can-
not believe in the wandering of adult Eels over wide stretches of land. According to Spallanzani,
in Comacchio, where for many centuries an eel fishery of immense extent has been carried on,
although these fish are found in numerous ponds and lagoons, the fishermen have never yet seen
an Eel wandering over the land; and once when, on account of the drying up of the water, the
Eels died by the thousand, not one of them made the attempt to escape by a short journey over-
land into the neighboring lake or into the river Po.

"The Eel occurs in all our waters, with the exception of small rapid brooks. The fishermen
distinguish many varieties based upon the differences in the form of the head or color and the
varying proportions in the length of the body and tail ; and the older ichthyologists have followed
their opinions without sufficient reason.

" By rapid growth the Eel attains the length of twenty-four to thirty inches, and often a greater
size. On account of their fat, which is very highly flavored, and the absence of bones, they are
everywhere valued, and are caught in various ways. The most profitable method of capture is in
eel-weirs and eel-baskets, and in traps by the use of nets, and on hooks they are also caught in
great quantities. In winter many Eels are taken with spears on the shelving shores where they
lie buried in the mud in a state of torpidity. In this fishery very often more are wounded than
captured, and, in addition to the large Eels, great quantities of small ones are taken."

Eel, continues Beuecke, has been an unsolved riddle since the time of Aristotle, and has given rise
to the most wonderful conjectures and assertions. Leaving out of question the old theories that the
Eels are generated from slime, from dew, from horsehair, from the skins of the old Eels, or from
those of snakes, and the question as to whether they are produced by the female of the Eel or by
that of some other species of fish, it has for centuries been a question of dispute whether the Eel is
an egg-laying animal or whether it produces its young alive ; although the fishermen believe that
they can tell the male and female Eels by the form of the snout. A hundred years ago no man
had ever found the sexual organs in the Eel.

Jacoby has remarked that the Eel was from the earliest times a riddle to the Greeks; while ages
ago it was known by them at what periods all other kinds of fishes laid their eggs, such discoveries
were never made with reference to the Eel, although thousands upon thousands were yearly applied
to culinary uses. The Greek poets, following the usage of their day, which was to attribute to

>A live and active Eel, a few days since, was dug mn from a depth of five feet in the soil of Exeter, New
Hampshire. Gloucester Telegraph, October 26, 1870.


Jupiter all children whose paternity was doubtful, were accustomed to say that Jupiter was also
progenitor of the Eel.

" When we bear in mind," writes Jacoby, " the veneration in which Aristotle was held iu ancient
times, and still more throughout the Middle Ages a period of nearly two thousand years it could
not be otherwise than that this wonderful statement should be believed, and that it should be
embellished by numerous additional legends and amplifications, many of which have held their
own in the popular mind until the present day. There is no animal concerning whose origin and
existence there is such a number of false beliefs and ridiculous fables. Some of these may be put
aside as fabrications ; others were, probably, more or less true, but all the opinions concerning the
propagation of the Eel may be grouped together as errors into three classes :

"I. The beliefs which, in accordance with the description of Aristotle, account for the origin of
the Eel on the basis of its development not from the mud of the earth, but from slimy masses which
are found where the Eels rub their bodies against each other. This opinion was advanced by Pliny,
by At liriKi'tis, and by Oppian, and in the sixteenth century was again advocated by Eondelet and
reiterated by Conrad Gessner.

" II. Other authorities base their claims upon the occasional discovery of worm-like animals
in the intestines of the Eels, which they described, with more or less zealous belief, as the young
Eels, claiming that the Eel should be considered as an animal which brought forth its young alive,
although Aristotle in his day had pronounced this belief erroneous, and very rightly had stated
that these objects were probably intestinal worms. Those who discovered them anew had no
hesitation in pronouncing them young Eels which were to be born alive. This opinion was first
brought up in the Middle Ages in the writings of Albertus Magnus, and in the following centuries
by the zoologists Leeuwenhoek, Eisner, Eedi, and Fahlberg ; even Linnaeus assented to this belief
and stated that the Eel was viviparous. It is but natural that unskilled observers, when they
open an Eel and find inside of it a greater or smaller number of living creatures with elongated
bodies, should be satisfied, without further observation, that these are the young of the Eel. It
may be distinctly stated, however, that in all cases where Eels of this sort have been scientifically
investigated, they have been found to be intestinal worms. 1

" III. The last group of errors includes the various suppositions that Eels are born not from
Eels, but from other fishes, and even from animals which do not belong at all to the class of fishes.
Absurd as this supposition, which in fact was contradicted by Aristotle, may seem, it is found
at the present day among the eel-catchers in many parts of the world.

"On the coast of Germany a fish related to the cod, Zoarces viviparus, which brings its young
living into the world, owes to this circumstance its name Aalmulter, or Eel Mother, and similar
names are found on the coast of Scandinavia."

"In the lagoon of Comacchio," continues Jacoby, "I have again convinced myself of the
ineradicable belief among the fishermen that the Eel is born of other fishes; they point to special
differences in color, and especially in the common mullet, Mugil :ephalus, as the causes of varia-
tions in color and form among Eels. It is a very ancient belief, widely prevalent to the present
day, that Eels pair with water-snakes. In Sardinia the fishermen cling to the belief that a certain
beetle, the so-called water-beetle, Dytiscus Boeselii, is the progenitor of Eels, and they therefore
call this 'Mother of Eels.'"

1 It is very strange that an observer so careful as Dr. Jacoby should denounce iu this connection the well-
known error of Dr. Eberhard, of Rostock, who mistook a species of Zoarccs for an Eel, and described the young,
which ho found alive within the body of its mother, as the embryo of the Eel. In Jacoby's essay, p. 24, he states
that the animal described by Eberhard was simply an intestinal worm, an error which will be manifest to all who
will take the pains to examine the figure.


DISCOVEBY OF THK FEMALE EEL. A scientific investigation into the generation of Eels
could only begin when, at tin- end of the Middle Ages, the prohibition which the veneration for
Aristotle li;id thrown over the investigations of learned men was thrown aside. With the revival
of the iiiitiinil sciences in the sixteenth century we find that investigators turned themselves with
;reat x.eal to this special question. There are treatises upon the generation of the Eel written by
the most renowned investigators of that period, such as Rondelet, Salviani, and Aldrovandi.
Nevertheless, this, like the following century, was burdened with the memory of the numerous
past opinions upon the eel question, and with the supposed finding of yonng inside the body of
the Mel.

The principal supporters of the theory that the Eel was viviparous were Albertus Magnus,
I.ecuwenhoek, Eisner, Redi, ami Fahlberg. The naturalists Franz Redi and Christian Franz
Panllini, who lived in the seventeenth century, must be mentioned as the first who were of the
n|iii)ion, founded, however, upon no special observations, that the generation of the Eel was in no
respect different from that of other fishes.

In the eighteenth century it was for the first time maintained that the female organs of the Eel
could certainly be recognized. It is interesting that the lake of Comacchio was the starting
point for this conclusion as well as for many of the errors which had preceded it. The learned
surgeon Sancassini, of Comacchio, visiting an eel fishery at that place in 1707, found an Eel
with its belly conspicuously enlarged; he opened it and found an organ resembling an ovary, and,
as it appeared to him, ripe eggs. Thereupon he sent his find, properly preserved, to his friend, the
celebrated naturalist Vallisneri, professor in the University of Padua, who examined it carefully,
and finally, to his own great delight, became satisfied that he had found the ovaries of the Eel.
lie prepared an elaborate communication upon the subject, which he sent to the Academy at
Bologna. 1

At the very beginning there were grave questions raised as to the correctness of this dis-
covery. The principal anatomical authority at Bologna, Professor Valsalva, appears to have
shared these doubts, especially since shortly after that a second specimen of Eel, which presented
the same appearance as that which was described by Vallisneri, was sent from Comacchio to
Bologna. The discussion continued, and it soon came to be regarded by the scientific men of
Bologna as a matter of extreme importance to find the true ovaries of the Eel. Pietro Molinelli
offered to the fishermen of Comacchio a valuable reward if they would bring him a gravid Eel.
In 1752 he received from a fisherman a living Eel with its belly much distended, which, when
opened in the presence of a friend, he found to be filled with eggs. Unfortunately the joyful
hopes which had been excited by this fortunate discovery were bitterly disappointed when it was
shown that the Eel had been cunningly opened by the fisherman and filled with the eggs of
another fish. The eel question came up again with somewhat more satisfactory results when, in
the year 1777, another Eel was taken at Comacchio which showed the same appearance as the
two which had preceded it. This Eel was received by Prof. Gaetano Monti, who, being iudis]K>sed
and unable to carry on the investigation alone, invited a number of his favorite pupils, among
whom was the celebrated Camillo Galvani, the discoverer of galvanism, to a council at. his
house. This Eel was examined by them all, and pronounced to be precisely similar to the one
which had been described by Vallisneri seventy years before. It was unanimously decided that
this precious specimen should be sent for exhaustive examination to the naturalist Mondini, who

1 1 fail to find any record of the publication of this paper, except that given by Jacoby, who states that it WM
printed at Venice in 1710, with a plate, and subsequently, in 171'2, under the title "De ovario Angnillarnra," in t.ho
Proceedings of the Leopold Academy.


applied himself with great zeal to the task, the results of which were published in May, 1777.
The paper is entitled "De Anguillse ovariis,'' and was published six years later in the Trans-
actions of the Bologna Academy. 1 Mondini was satisfied that the supposed fish which Vallisneri
described was nothing but the swimming bladder of the Eel in a diseased state, and that the
bodies supposed to be eggs were simply pustules in this diseased tissue. In connection with this
opinion, however, Mondiui gave, and illustrated by magnificent plates, a good description and
demonstration of the true ovaries of the Eel, as found by himself. This work, which in its
beautiful plates illustrates also the eggs in a magnified fold of the ovary, must be regarded as
classical work, and it is an act of historic justice to state that neither O. F. Miiller nor Eathke,
but really Carlo Mondini, was the first discoverer, describer, and demonstrator of the female
organs of the Eel, which had been sought for so many centuries. 2

Three years later, entirely independent of Mondini, the celebrated zoologist Otto Friedrich
Miiller published his discovery of the ovary of the Eel in the "Proceedings of the Society of
Naturalists" at Berlin. 3

The discovery of Mondini was next specially brought into prominence through Lazzaro
Spallanzaui. This renowned investigator, in October, 1792, went from Pavia to the lagoons of
the Po, near Comacchio, for the sole purpose of there studying the eel question. He remained
at Comacchio through the autumn ; he was, however, unable to find anything that was new
regarding the question, but in the report upon his journey of investigation he entirely threw
aside the discovery of Mondini, and announced that the ovaries discovered by this authority were
simply fatty folds of the lining of the stomach. 4

"It was without doubt this absolute negative statement of such a skilled investigator as
Spallanzaui which for a long time discouraged further investigations on the. eel question, and
allowed what had already been discovered to be regarded as doubtful, and finally to be forgotten.
So when Professor Rathke, of Kb'nigsberg, in his assiduous labors upon the reproductive organs
of fishes, in the year 18U4, described the ovaries of the Eel as two cuff'-and-collar shaped organs
on both sides of the backbone, and in the year 1838 described them as new, he was everywhere
in Germany (and to a large extent to the present day) regarded as the discoverer. 4 The first
picture of the ovary after that of Mondini, and the first microscopical plate of the egg of the Bel,

1 Do Bononiensi Scientiarom et Artium Institute atque Academia Commentarii. Tomus VI. Bonouiao, 1783, pp.
406 f ( seq.

'Prof. G. B. Ercolani, of Bologna, and also Crivelli and Maggi, in their essays published in 1872, have rightly
stated that Mnndini's priority of discovery has been overlooked in Germany. Neither Rathke nor Hohnbaum-
Hornscbcch nor Schltiser have mentioned his work. S. Nillson, in his "Skandinavisk Fauna," 1855, says nothing of
Mondini. He mentioned as the first discoverer of the ovaries O. F. MUller, while Cuvier, in his " Histoire Naturelle
des Poissons," assigns the honor rather to Rathke. Th. von Siebold is the first to announce in his work, published
in 1863, "Die Siisswasserfische von Mittelenropa," page 349, that Mondini, almost contemporaneously with O. F.
MUller and independently of him, discovered the ovaries of the Eel. The error, as was discovered by Italian zoologists
later than by those of Germany, arose from the fact that the announcement of Miiller's discovery was printed in 1780,
while that of Mondini's, which was mavle in 1777, was first printed in 1783.

"O. F. MtlLLER: BemUhungen bei den IntBtinal-wtirmern. Schriften, Berlin. Gesellschaft, i, 1780, p. 204.

4 "Rathke, who first, since Mondini, has in detail described (1824, 1838, and 1850) the ovaries of the Eel, is con-
sidered by some to have recognized them; but this, however, is not true, the additions made by him to Mondini's
description being to a great extent erroneous. It is not true that the transverse leaflets are wanting in the ovaries
of the Eel, as he asserts in his last work, contrary to his former description, which was probably based on the law
of analogy, and that thereby they are distinguished from those of the salmon and sturgeon. It is not true, what
Rathke likewise asserts, that the genital opening of the Eel consists of two small canals, for I have invariably only
found one, which opens in the urethra. Rathke has certainly described the eggs quite exactly, distinguishing the
larger whitish oucs, having a diameter of about one-fifteenth of a line, and the smaller transparent ones, with the
germinal vesicle inside ; but Mondini likewise says: "inmimerait ipluErula* miniman, cei/uales, pellucidas, divisae tamen,
I/IK: in centre mactilam osttndebant, ecc. rirfi," thus showing the true nature of the ovaries and the eggs, and contrasting
them with the fatty formation and with the ovaries and eggs of other osseous fish." STRSKI.


i lloinsclnicli presented in a dissertation published in 1842 a paper which should be
rightly consider. -d .1- \' -n-.it importance in the literature of this question. The questions
concerning tin- ovaries of tin- Kel may be regarded as having been brought to a distinct con-
clusion by Kathkc, who, in the year 1850, published an article describing a gravid female
Kel. tin- tiist and only gravid specimen which had, tip to that time, come into the hands of an

DISCOVERY OF THE MALE EEL BY SYRSKI. The history of the search for the female of the
Kel having been given, for the most part, in a translation of the work of Dr. Jacoby, it seems ap-
propriate to quote the same author concerning the search for the male Eel, which, though much
shorter, is none the le interesting.

In the dissertation of Holinbaum Hornschuch, published in 1842, the opinion was expressed
that certain cells found by the author in the ovaries, which differed from the egg cells by their form
and contents, should be regarded as the spermary cells of the Eel, and that the Eel should be
regarded as hermaphrodite. Six years later Schluser presented an interesting dissertation upon
the sexes of Lampreys and Eels in which he pronounced these opinions of Hohnbaiiin-Hornschuch
to be erroneous, and expressed the opinion that the male Eel must be extremely rare, or that it
was different, perhaps, from the female. From this time up to the beginning of 1870, a male Eel
was never seen, nor do we find any opinions expressed concerning the form of the male of the Eel
or its reproductive organs. 2

According to Robin, in 1846 George Louis Duveruoy (Cuvier, Anatomic compared, 6<1. 2, 1848,
tome viii, p. 117) described the ruffle tube type of the testis of the Lampreys and Eels, with the
free margin festooned in lobules, shorter to the right than to the left, like the ovaries, etc. He
added: "At the .breeding season we perceive in it an innumerable quantity of granulations, or
small spermatic capsules, the rounded form of which has often led to their being confounded with
the ovules, at least in the Eels, in which, in reality, these capsules are nearly of the same size
as the ovules, but the latter are distinguished by their oval form." The ovules are spherical, and
not oval; but the other facts aTe fundamentally correct. It is also in error that Duvernoy adds
(p. 133): "The Eels and the Lampreys have no deferent canal, any more than an oviduct. Like
the ova, the semen ruptures the capsules in which it has collected and diffuses itself in the abdom-
inal cavity, whence it is expelled in the same way as in the ova."

By some droll coincidence the University of Bologna, and soon after that of Pavia, were
again prominent participants in the eel tournament. At the meeting of the Bologna Academy,
December 28, 1871, Prof. G. B. Ercolani read a paper upon the perfect hermaphroditisin in the
Eel. 3

Fourteen days later Prof. Balsamo Crivelh and L. Maggi read a detailed and elaborate paper
upon the "true organs of generation in Eels." These investigators, without concerted action, had

Online LibraryG. Brown (George Brown) GoodeThe fisheries and fishery industries of the United States (Volume 1:1) → online text (page 107 of 146)