G. Brown (George Brown) Goode.

The fisheries and fishery industries of the United States (Volume 1:1) online

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a reaction with protoplasm if diluted to the extent of one part to a million of water.

PROBABLE CAUSE OF THE GREEN COLOR. It is highly probable that the green color of the
Oyster is due to the absorption from its food of a harmless vegetable pigment. In this country
green-bearded Oysters occur at Lynn Haven Bay, Hongers and York itivers, Virginia, on the



OBSKIIVATIONS or <;.\IU.ON AND JOHNSTON. 737

:oast of New Jersey, in New York Bay. ami Long Island Sound. 1 have Been specimens (tarn a
number of these localities, and also tasted thcin both raw and cooked without being able to detect
any disagreeable or apparently harmful flavor.

I Matoins and -reen algre occur in great abundance in the stomach of the Oyster, especially the
former. The intestine is sometimes packed with countless numbers of the empty frustulesor test*
of diatoms, mixed with dark, muddy ooze or sediment and very line particles of saud or quurtz.
It has been objected that the green color could not be derive*! from diatoms, because these organ
ism- are. as a rule, apparently brown rather than green. This objection I find to bo based II|MHI
a misapiirehfusiou of the structure of the Mntomaceof, m maybe galhered from the following
general statement taken from Sachs' "Text Book of Botany," one of the latest and highest
authorities. On page 2li2 he says: "The diatoms are the only algaj except the Conjugate in which
ihe ehlorophyl occurs in the form of disks and bands, but in some forms it is also found in grains.
and the green coloring matter is concealed, like the cblorophyl grains in Fucacea; by a buff-colored
substance, diatomine or phycoxanthine." It appears, then, according to the foregoing quotation,
that it is not impossible for diatoms to be the cause of the green tint in Oysters, which, let me
remark, is very nearly that of some pale green forms of those organisms which I have observed in
water from oyster coves where I have conducted microscopic studies. Both green and brown
diatoms may frequently be found in the stomach, and in making examinations to discover them 1
find it best to thrust the nozzle of a pipette directly into the stomach through the mouth and
(esophagus. The pipette should have a compressible bulb, so as to enable one to draw up the
contents of the gastric cavity into the tube without injuring the animal or taking up any fragments
of it to vitiate the experiment.

OBSERVATIONS OF GAILLON AND JOHNSTON. Speaking of the abundance of the Naricula
otreari of Kiitzing, M. Benjamin Gaillon, in 1820, said that they inhabit the water of the
tanks or " parks" in which the Oysters are grown in such immense abundance, at certain seasons
of the year, that they can only be compared to the grains of dust which rise in clouds and
obscure the air in dusty weather. Dr. Johnston, speaking of the French Oysters, says that in
order to communicate to them a green color, which, as with us (in England), enhances their
value in the market and in the estimation o e the epicure, they are placed for a time in tanks
or "parks," formed in particular places near high-water mark, and into which the sea can lie
admitted at pleasure by means of sluices; the water being kept shallow and left at rest is
favorable to the growth of the green Conferva; and Ulvce; and with these there are generated
at the same time innumerable crustaceous animalcules which serve the Oysters for foot! and
tincture their flesh with the desirable hue.

This last remark of Dr Johnston's at first struck me as improbable, but I have met with great
numbers of small crustaceans, Copepoda mainly, in the branchial cavity of the common Clam (Mya
arenaria). Certain peculiar species have also been described by Allman from the branchial
cavities of ascidians. More recently, while investigating the contents of the stomach of the
Oyster, by the method already described, I find that it also swallows crustaceans, which are digested
and absorbed as food. The tests of nauplii or very minute larval crustaceans with the contents
digested out were frequently met with. Doubtless many very small Copepoda are also swallowed
and digested, but these are not green. Besides the foregoing, I sometimes met with the. very young
.-hells of larval gasteropoda and laniellibrauchs: indeed, it is not improbable that the adult Oyster
may consume its own larva?. The remains of bryozoa were also observed, such a-s Pedicellina
inni'i-ii-tiiin. The test of a peculiar elongate rhizopod and the cephalula stage of several worms
were also noticed. Of the smaller organisms usually associated with more or less clearly marked
47 F



738 NATURAL HISTORY OF AQUATIC ANIMALS.

putrefactive changes, one which I find almost uniformly present is a filiform or thread-like organ-
ism allied to Spirillum. It, however, was always found in the stomach in great abundance, and
especially in the pyloric portion of the intestine in which the crystalline style is lodged. This
organism is probably harmless; a similar one is frequently found in both fresh and salt water,
and has at times been developed in prodigious numbers in the reservoirs from which the supplies
of water were drawn for a large city, without any evidence of its having produced a harmful
effect upon those who drank of the water.

VIEWS OF LEIDY, PUYSEGUR, AND DECAISNE. Professor Leidy, at a recent meeting of
the Academy of Natural Sciences of Philadelphia, stated it as his belief that Oysters feed at
times on the zoospores of certain algae, as those of Ulna latissima (sea cabbage), which he knew
from personal observation to be green, and which he thought might possibly be the cause of
the green coloration of the soft parts of the animal as sometimes observed in certain localities.
Very possibly this may be the case, but judging from what I have seen and heard from oyster-
men, as well as from what I have read in various publications relating to this matter, I am not
inclined to regard this as the only source of the unusual green tint of the flesh of the Oyster.
I hope to be able to show that it is probably of vegetable origin, and therefore quite harmless.
That it is not copper we may be equally certain, as Professor Lewis' tests have shown, for
any such quantity of a copper salt as would produce the green gills, heart, and cysts in the
mantle, such as are often observed, would, without doubt, be as fatally poisonous to the Oyster
as to a human being. The source of the green has recently been investigated by two French
savants, MM. Puysegur and Decaisne, who found that when perfectly white-fleshed Oysters
were supplied with water containing an abundance of a green microscopic plant, the Navicula
ostrearia of Kiitzing, their flesh acquired a corresponding green tint. These investigators also
found that if the Oysters which they had caused to become imbued with this vegetable green
were placed in sea- water deprived of the microscopic vegetable food the characteristic color would
also disappear. Whether this will finally be found to be the explanation in all cases remains to
be seen, as some recent investigations appear to indicate that it is possible that a green coloration
of animal organisms may be due to one of three other causes besides the one described above as
the source of the green color of the Oyster.

GEDDES UPON CHLOBOPHYL-CONTAINING ANIMALS. Patrick Geddes, in a recent number
of "Nature," has pointed out that the "list of supposed chlorophyl-containing animals . . ^
breaks up into three categories: first, those which do not contain chlorophyl at all, but green
pigments of unknown function (Bonellia, Idotea, etc.); secondly, those vegetating by their own
intrinsic chlorophyl (Convoluta, Spongilla, Hydra); thirdly, those vegetating by proxy, if one may
so speak, rearing copious algae in their own tissues, and profiting in every way by the vital
activities of these." This latter is one of the most interesting and important of modern biological
discoveries, that living animal bodies may actually afford a nidus for the propagation of green
microscopic plants and not be injured but rather be benefited thereby. The oxygen thrown
off by the parasitic vegetable organism appears to be absorbed by the tissues of the animal host,
while the carbonic acid gas thrown off by the latter is absorbed by the vegetable parasite, thus
affording each other mutual help in the processes of nutrition and excretion. This singular
association and interdependence of the animal host and vegetable guest has received the some-
what cumbrous name of Symbiosis, which may be translated pretty nearly by the phrase "asso-
ciated existence." This is not the place for the discussion of the purely scientific aspect of this
question as already ably dealt with by Dr. Brandt, Patrick Geddes, Geza Entz, and others, and



mi: <;KI:I:N MATTKK IN ANIMALS. 739

we will therefore only notice their researches in so far as they appear to have a bearing IIJMMI
the origin of tlie given color of the Oyster.

KM/' DISCOVERIES. Entz has discovered that he could cause colorless infusoria to become
iieen liy feeiling with green palmcllaccon.s cells, which, moreover, did not die after the death of
their hosts, but continued to live, growing and developing within the latter until their total evolu-
tion proved them to be forms of very simple microscopic green algie, such as Palmella, Qlirocyti*,
etc. My own observations on some green-colored infusorial animals have been of so interesting a
character that I will here describe what I observed in a green bell animalcule (Vorticella rhloro-
Klliimn). UIK>U investigating their structure, I found that next the cuticle or skin in the outer soft
layer of their bodies, known as the "ectosarc," at all stages there was a single stratum of green
corpuscles very evenly or uniformly imbedded. In another form (Stentor), as already noticed by
Stein, the same superficial layer of green corpuscles was observed, reminding one very forcibly of
the superficial layer of chlorophyl grains observed in the cells of some plants, as, for instance,
Amichari*. Now, it is well known that certain animalcules are at times quite colorless and at
others quite green; this appears to 1)6 the case with Ophrydium. In this last case I have a
suspicion that vegetable parasites may be the cause of the green variety, but as for the others,
Sh-ntor and Vorticella, I am not so sure that their green forms are so caused. In them the
superficial positions of the green corpuscles and their behavior toward reagents lead me to
think that they must be regarded as integral parts of the creatures in which they are found.

NATURE OF THE GREEN MATTER IN ANIMALS. A grass-green planariau worm (Conroluia
Schultzii), found at RoscofF by Mr. Geddes, was observed by him to evolve oxygen in largo
amounts, like a plant, and "both chemical and histological observations showed the abundant
presence of starch in the green cells; and thus these planarians, and presumably, also, llt/ilm,
Hf)onyilla, etc., were proved to be truly vegetating animals." While some organisms, like the
foregoing, appear to have true chlorophyl grains imbedded superficially in their own substance,
others, like the radiolariaus, some siphonophores, sea anemones, and jelly-fishes, harbor true
vegetable parasites, or, preferably, vegetable guests.

That the green observed in a number of animal organisms is of the nature of chlorophyl,
or leaf green, has been proved by Lankester by means of the spectroscope. A. W. Bennett, in
alluding to Lankester's observations, says: "In all cases the chlorophylloid substance agrees in
having a strong absorption band in the red a little to the right or left and, except in Idotea, in
being soluble in alcohol, and in having strong red fluorescence, and in finally losing it color when
dissolved."

The vegetable organisms which have been found to inhabit the lower forms of life alluded to
in the foregoing paper have been regarded as belonging to two genera, which Dr. Brandt has
named ZouchloreUa and ZooxantheUa, and which are probably in part synonymous with the genus.
1'hilozoiin, afterwards proposed by Mr. Geddes. The latter gentleman, however, claims to have
first demonstrated the truth of the view that the yellow cells of radiolarians and polyps are alga?;
secondly, the foundation of the hypothesis of the lichenoid nature of the alliance between alga>
and animal into a theory of mutual dependence; and, thirdly, the transference of that view from
the region of probable speculation into that of experimental science.

Hitherto no one has apparently noticed the occurrence of green vegetable parasites in
bivalve inollnsks except Professor Leidy, who has very kindly permitted me to use the facts
observed by him relating to Aitodan, one of our common fresh- water Mussels. In this animal ho
some years ago observed what must be considered to be algous parasites. He found them in
great numbers infesting the tissues of the Mussel and of a larger size than the nuclei of the cells of
the host in which they were imbedded. They were also provided with a nucleus, and were, there-



740 NATURAL HISTORY OF AQUATIC ANIMALS.

fore, not a part of the animal but a distinct vegetable organism. These facts, observed a long
time since, render it very probable that Processor Leidy was one of the first to notice the intra-
cellnlar parasitism of a plant in an animal.

The green color of the Oyster, as far as my experience goes, is not intense, as in many green
animals, snch as we observe in Stentor, Spent/ilia, Hydra, etc., but is a pale pea-green tint. This
has been found to be the color of affected natives as well as of foreign ones, the gills and mantle
being usually most distinctly tinged. Exceptionally the heart is affected, its color sometimes
being quite intense.

EXPERIMENTS UPON EUROPEAN OYSTERS. In studying some Oysters which were obtained
from England through the kind offices of Messrs. Shaffer and Blackford, in response to a request
coming from Professor Baird, certain ones were found which were decidedly green. Of these the
French specimens of Ostrea edulis, and a very singular form, labeled "Anglo-Portuguese," had the
gills affected, and in some of the latter the liver, heart, and mantle were very deeply tinged in
certain parts, so much so that I decided to make as critical an examination as my resources could
command.

Spectroscopic investigations gave only negative results, as it was found impossible to discern
any positive evidence of chlorophyl from the spectrum of light passed through thin preparations
made from specimens of green-tinted Oyster, some of which, like those made from the heart, are
decidedly green to the naked eye. There was no absorption noticed at the red and blue ends of
the spectrum, such as is observed when the light which enters the slit of the spectroscope first
passes through an alcoholic solution of leaf green or chlorophyl ; indeed, the spectrum did not
appear to be sensibly affected by the green substance which causes the coloration of the Oyster.
No attempt was made to test the matter with the use of alcoholic green solutions obtained from
affected Oysters, as the former are not easy to get with a sufficient depth of color, because of the
relatively small amount of coloring matter present in the animals. Unstained (fresh) preparations
were used in all of these experiments.

COLORS IN DIFFERENT PARTS. I find the liver to be normally of a brownish-red color in
both the American and European Oyster, sometimes verging toward green. When the flesh or
gills of the animal is green, the liver almost invariably partakes of this color, but in an intensi-
fied degree. The green stain or tincture appears in some cases to have affected the internal ends
of the cells which line the follicles or ultimate saccules of the liver. This color is able to survive
prolonged immersion in chromic acid and alcohol, and does not allow carmine to replace it in
sections which have been stained with an ammoniacal solution of that color, the effect of which
is to produce a result similar to double staining in green and red. The singular green ele-
ments scattered through the connective tissue remain equally well defined, and do not take the
carmine* dye. I at first believed these to be parasitic vegetable organisms, and I also sup-
posed I saw starch granules in them, which physical tests with an iodine solution failed to con-
firm. These large and small green granular bodies in the connective tissue, and those close to
the intestinal wall, as well as those in the heart I, find present in fewer numbers in white-fleshed
Oysters, but simply with this difference, that they are devoid of the green color. It is evident,
therefore, that they cannot be of the nature of parasites, though the color is limited to them,
only the surrounding tissue, except in the region of the heart, appearing of the normal tint.
This condition of the specimens observed by me does not, however, disprove the possibility of
the occurrence of vegetable parasites in the Oyster, where there is as much, or perhaps more
likelihood of their occurring than in some much more highly organized animals.

It is a fact, however, that the Oyster is singularly free from true parasites of all kinds; the



COLORS OF DIFFERENT PARTS OF THE OYSTER. 741

o\st-i- crab IHMIIJ: perhaps the only creature which is ever frequently found within it* valves,
and tlu-n only as a harmless messmate. More recently it has IM-CH my good fortune to be able to
study a second lot of European Oysters, in two varieties of which the green color was unusually
developed, especially in the heart. In a specimen of Falmouth Oyster 1 found a large cyst or
sac in the mantle near the edge filled with green cells, which, like those in the heart, when opened
reaiiiK x'parutcd from one another, being quite as i 1 dependent of each other as the ordinary
discoidal corpuscles in the serum of red blood. The hearts of affected specimens were found to
ha\r I lie wall of the ventricle abnormally thick, and covered inside with the readily detachable
green cells in a thick layer and measuring one three-thousandth of an inch in diameter. An appli-
cation of the test for starch with iodine gave a negative result. If iodine was first applied to
these cells in strong solution, and they were then treated with sulphuric acid, the characteristic
blue reaction was not developed, showing that there was no cellulose wall covering them, and
that they were most positively not parasitic, algous vegetable organisms. In potassic hydrate
solution they were completely dissolved, a further proof of the absence of cellulose.

Their dimensions, one three-thousandth of an inch, is the same as that of the blood cell of the
Oyster. They are nucleated, with the nucleus in an eccentric position as in the blood-cell of the
animal. Their occurrence in the heart and gills so as to tinge those organs of their own color is
almost positive proof of their true origin and character. Furthermore, I find in sections that they
sometimes occlude the blood-channels. In the cysts in the mantle, as in the heart, they are free,
and in the normal untiiigcd heart they are not abundant. All of the foregoing facts indicate that
these green bodies are in reality blood-cells which belong to the animal. How they become green
is not easy to determine. The fact remains that no evidence of the presence of green Micrococci
or Microbia, as independent existences, could be made out. The fact that I found instances in green
Oysters where an unusual greenish material was found in the follicles .of the liver, the living cells
of which were also affected, would indicate that the color was probably absorlrcd from the fowl of
the animal, which, as we know, consists largely of living vegetable matter. It is not improbable
that the tinged nutritive juices transuded through the walls of the alimentary canal acquired the
color of the fowl which hail been dissolved by the digestive juices.

How to account for the accumulation of the green cells in the heart and in cysts in the
mantle is not, however, an easy matter, unless one be permitted to suppose that the acquisition
of the green color by the blood-cells is in reality a more or less decidedly diseased condition, for
which we have no ground in fact, since the green Oysters are in apparently as good health as the
white ones. They were found 'fat' or 'poor,' just as it may have happened that their food was
abundant or the reverse. They are also found in all stages of the ' greened' condition. Sometimes
they have only a very faint tinge of the gills, or they may be so deeply tinged as to appear
unpalatable, with the heart of a deep green, or with green cysts developed in the mantle, or with
clouds of this color shading the latter organ in certain places. A vastly greater pro|>ortion of
green Oysters are eaten in this country, at all events, than is generally supposed, especially of
those just faintly tinged in the gills.

The most important glandular appendage of the alimentary tract of the Oyster is the liver.
It communicates by means of a number of wide ducts with a very irregularly formed cavity, which
we may designate as the stomach proper,- in which the food of the animal comes into contact with
the digestive juices poured out by the ultimate follicles of the liver, to undergo solution preparatory
to its absorption during its passage through the singularly formed intestine.

If thin slices of the animal are examined under the microscope we find the walls of the
stomach continuous with the walls of the great ducts of the liver. These great ducts divide and



742 NATURAL HISTORY OF AQUATIC ANIMALS.

subdivide until they break up into a great number of blind ovoidal sacs, into which the biliary
secretion is poured from the cells of their walls. A thick stratum of these follicles surrounds the
stomach, except at its back or dorsal side. It is not correct to speak of the liver of the Oyster as
we speak of the liver of a higher animal. Its function in the Oyster is the same as that of three
different glands in us, viz, the gastric follicles, the pancreas, and the liver, to which we may add the
salivary, making a total of four in the higher animals which is represented by a single organ in
the Oyster. In fact, experiment has shown that the secretion of the liver of mollusks combines
characters of at least two, if not three, of the glandular appendages of the intestine of vertebrated
animals. There are absolutely no triturating organs in the Oyster for the comminution of its
food ; it is simply macerated in the glandular secretion of the liver and swept along through the
intestine by the combined vibratory action of innumerable fine filaments with which the walls of
the stomach, hepatic ducts, and intestine are clothed.

In this way the nutritive matters of the food are acted upon in two ways : first, a peculiar
organic ferment derived from the liver reduces them to a condition in which they may be absorbed ;
secondly, in order that the latter process may be favored it is propelled through an intestinal
canal which is peculiarly constructed so as to present as large an amount of absorbent surface as
possible. This is accomplished by a double iuduplication or fold which extends for the whole
length of the intestine, the cavity of which in consequence appears almost crescent shaped when
cut straight across. On the concave side the intestinal wall is thrown into numerous very narrow
longitudinal folds, which further serve to increase the absorbing surface. Such minor folds are
also noticed in the stomach, and some of these may even have a special glandular function. There
are no muscular fibers in the wall of the intestine as in vertebrates, and the sole motive force
which propels the indigestible as well as digestible portions of the food through the alimentary
canal is exerted by the innumerable vibratory cilia with which its inner surface is clothed. The
intestinal wall is wholly made up of columnar cells which are in direct contact externally with
the connective tissue which is traversed by numerous large and small bloodvessels devoid of
specialized walls.

This apparatus is admirably suited to render the microscopic life found in the vicinity of the
animal available as a food supply. The vortices created by the innumerable vibratory filaments
which cover the mantle, gills, and palps of the Oyster enables it to draw its food toward itself,
and at the same time the microscopic host is hurled into the capacious throat of the animal to
undergo conversion into its substance as described above. The mode in which the tissues may
become tinged by the consumption of green spores, diatoms, or desmids it is easy to infer from



Online LibraryG. Brown (George Brown) GoodeThe fisheries and fishery industries of the United States (Volume 1:1) → online text (page 123 of 146)