G. Brown (George Brown) Goode.

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down mainly in the substance of the mantle. It is this relatively large amount of delicate, easily-
digested protoplasm, stored up in the palps and mantle, which renders the Oyster so wholesome
and nutritious.

The deposition of this protoplasmic material in the mantle, palps, and body stands in intimate
relation to the activity of the reproductive organs. During the spawning season Oysters are said
to be " poor," that is to say poor in condition, for at this time the mantle, especially where it lies
next the body on each side, is very thin and quite transparent ; the radiating pallia! muscles along
the border of the mantle, as well as Us vessels and nerves, may now be readily studied under the
microscope, owing to its transparency and the absence of opaque granular protoplasm. If we
examine the reproductive organs at this time, as a rule, we will find them greatly developed and
pouring out their products through two large ducts, the combined caliber of which is not far short
of that of the intestine. It will be evident to any thinking mind that if the major part of the food
material elaborated by the digestive and nutritive systems goes to the ovaries or testes to be
transformed into sex products, which are continually thrown off during the breeding season, little
of such Material can be stored up in the tissues of the body. We have described exactly what
happens. In the month of September, when the Oysters in this latitude are for the most part
done spawning, the drain of elaborated material having ceased to flow from the openings of the



FATTKNIXG OF OYSTERS. 755

reproductive organs, it is diverted in another direction, but is retained in the system and has to be
deposited somewhere in the hotly. The most extensive deposits of this elaborated living matter
occur in the mantle, body, and palps, the color of which rapidly changes from the watery, trans
parent condition prevalent during the spawning season to a creamy white. The whole animal also
acquires a solidity which it did not possess before; it loses its watery, impoverished appearance,
together with its disposition to shrink to a fraction of its original bulk from an extensive loss of
fluids when opened. The mantle and palps become opaque and thicker than before, and their
substance is softer and more easily lacerated. The change here described undoubtedly affects the
connective tissue principally, as elsewhere stoted. The material of the latter has the milky
apjMMirance of the reproductive organ when mutilated, and may readily be mistaken for the latter
by the inexperienced. It appears that the generative and nutritive functions are opposed to each
other in the Oyster as in other animals; all of which indicates, too, the amount of energy which
must be expended during the breeding season in the production of germs. Whatever surplus
nutriment is stored up in the winter appears to be immediately devoted to the formation of germs
upon the arrival of the warm months, when food is also probably most plentiful and when the
external conditions are right for the development of the embryos. The eftbrt which the Oyster
makes, at the expense of so much material, to reproduce its kind ought to be respected. In the
protection of the Oyster during the close season we are simply following the dictates of experience
and common sense.

The account which we have given above of the physiology and interdependence of the
fattening and reproductive processes of the Oyster, it seems to me, affords an opportunity to
point out how little philosophy there is in the doctrine that Oysters may be fattened by putting
them for a day or two in water less salt than that from which they were first taken, in order that
they may be water-swollen by the action of osmose, so as to give to them a plump appearance.
It is surprising how little dependence is to be placed upon the statements of oystennen and
fishermen in regard to the habits of the objects with which they are supposed to be most familiar.
And this statement, like many others of a similar kind, has no basis of fact and experimental
evidence to rest upon. I may sum np the utter absurdity of the widespread belief in the possi-
bility of fattening Oysters by removing them from salt to less salt water for a few days, by
saying that it amounts to the same thing as to assert that water is a fatty or oleaginous substance!

The results of my most recent investigations upon the minute anatomy of Ostrea virginica may
be fitly described in this place, since they have an important bearing upon the process of fattening.
The subject of this investigation was one of the most impoverished-looking Oysters which it has
ever been my fortune to find. It was collected on the 20th of July this present year (1882) and
placed in a chromic acid solution of one per cent for forty-eight hours, when it was washed and
finally transferred to alcohol, to be cut into sections when convenient. This I have recently done*
When the specimen in question was fresh it was characterized by the almost perfect transpar-
ency of the mantle, and, as it afterwards turned out. the total atrophy of the generative organ.
Before the hardening process had been undergone, the mantle was greatly distended by watery
fluid, so much so that, after hardening, it had shrunken to about one-tenth of its bulk while m
the fresh and living state. The hardened specimen was cut into thin sections after imbedding in
paraffine, by means of a modification of the Taylor freezing microtome; the sections for thinness
left nothing to be desired, and revealed a condition of things different from any previously
observed by the writer in sections of either native or foreign Oysters. A careful microscopic
scrutiny showed that nowhere in the section was there a trace of even a rudiment of the genera-
tive network described as the atrophied condition in a previous portion of this paper. Not even



75G NATURAL HISTORY OF AQUATIC ANIMALS.

a trace of the connective tissue in which the rudiments of the latter are usually imbedded
remained, but the hepatic follicles or ultimate saccules of the liver were lying in immediate
contact with the mantle, with no tissue whatever intervening. 1 have hitherto found the liver
surrounded by a thick stratum of connective tissue in all of the specimens examined. The state-
ments in a previous portion of this essay in regard to the existence of vessels which traverse this
connective tissue mass will therefore have to be modified so far as to say that not only does the
connective tissue of the body mass completely disappear, but also the vessels themselves which
are excavated through its substance.

Turning now to the condition of the mantle, I find this in a no less remarkable state than the
parts already described. The " vesicular connective tissue cell*," as they have appeared to me
hitherto, have given place to an entirely different structure, apparently much less solid and
substantial. Instead of the clearly defined coarsely cellular structure usually noticed in sections
made from less impoverished individuals, the tissue has now become very coarsely areolar, all trace
of the peculiar nuclear bodies having vanished, together with the internal protoplasmic network
which they so clearly exhibit. The areolae inclosed by the fibers of the connective tissue of the
mantle are very coarse and may measure as much as half a millimeter across in sections of the
hardened and shrunken specimen. When the mant'e was gorged in life, with blood probably, some
idea of the coarseness of these meshes may be formed. The meshes may then have measured four
or five millimeters in diameter, the resulting cavernous state of this highly elastic tissue enabling
the mantle to become gorged or swollen by endosmosis to a remarkable degree, so much so as to
cause the animal to be apparently bulky, yet in reality distended with sanious fluids merely. The
question now arises, What has become of this connective tissue which has so completely disap-
peared f The only interpretation which I can offer is that the connective tissue substance has
been transformed into sexual products which have been poured out by way of the efferent sexual
ducts, and ihat our specimen represents the extreme of exhaustion consequent upon the completed
exercise of the reproductive function for the season. The animal, in other words, has now exhausted
ite germ-producing resources, and must begin to feed and store up material for the next season's
generative products. It therefore becomes highly probable that the reproductive organs develop
anew each season. My reason for thinking so is, that in this specimen the atrophy or wasting
away of the reproductive organ has gone so far that no trace even of the efferent ducts of that body
remains. The specimen, taken as it was in July, also shows that the spawning season may be
completed before the end of summer.

The connective tissue of the Oyster is, therefore, in reality transformed into ova and sperma-
tosoa, depending simply upon the sex of the individual whether it shall be the former or the latter.
This also raises the question whether the same individual may not be of a different sex during
different seasons, since it appears that the whole reproductive organ disappears and develops anew
every year. This it is however to be noted is arguing from a very different basis from that of
some foreign writers who have been absurdly illogical enough to say that the Oyster was of a
-different sex in different years, apparently forgetting that it would be impossible to open the same
individual twice in succession; since opening it kills the animal and puts the second examination
totally out of the question.

The function of the mesenchymal or connective tissue in the Oyster is, therefore, of the nature
of a store of reserved material protoplasm laid up for the purpose of conversion into germs as the
reproductive organ develops anew. It is then in the highest degree improbable that it is of the
nature of an oily or fatty substance, out of which it would be impossible to form such highly vitalized
bodies as the ova and spermatozoa of the Oyster. While it is true that we find the mesenchymo



rroN TIIK i-\i H:\INI; OF OYSTERS. 757

developed to tin 1 greatest extent during the winter when it may l>e said the Oyster is in the
lies! eondition as regards tlesli, it does not follow that this plumpness is due to fatty matters, but
father to a larger amount of protoplasm tilling up the mantle, palps, and body mass.

Our sections of the specimen described above show some other singular features which cannot
be passed over in silence. The principal of these is the presence of thick-walled vessels in thu
ventral lobes ot the mantle. In life we lind branching vessels visible in the transparent mantle in
\ cry impoverished specimens, such as the one under discussion. These vessels may be followed to
what are apparently their ultimate ramifications and seem to end abruptly. It is these vessels
which become obscured when the animal acquires tlesh; they are, in fact, hidden in the thick
deposit of connective tissue laid down in the mantle. They are grayish or whitish in color as they
shimmer through the transparent external epithelial and connective tissue layers of the mantle
organ. They are also different in character from other vessels excavated in the connective tissue
of the mantle, and which disappear with the atrophy of the hitter's substance, just as we noticed
was the case with the vessels of the body mass. In a specimen as greatly impoverished us the one
under discussion, the thick-walled pallial vessels become very conspicuous in transverse sections.
They may not have the same function as the bloodvessels of the ordinary wall-less form found in
the connective tissue, from which type they may be at once distinguished by their thick, finely
cellular walls.

The almost total atrophy of the mesenchyrac or jnesoblast during the spawning season is a
very remarkable fact, no less so than its regeneration. It appears, however, as far as I have been
able to learn from transverse sections of very small spat, one-eighth to one-sixteenth of an inch
in diameter, that the absence of a well -developed connective tissue deposit also characterizes the
soft parts of the young animal. Indeed, the liver follicles here are relatively few in number,
whereas they are very numerous in the adult. The follicles in the young also lie in immediate
contact with the mantle, resembling in this respect the spawn spent adults. This, for einbryolo-
gical reasons, ought to be so. We find, in fact, according to the unanimous testimony of observers,
that the mesoblast in the Oyster develops by the proliferation of cells from the outer and inner
layers into the segmentation or body cavity. Why, then, should it not be absorbed and regener-
ated in the same way in the adult f There seems to be no valid reason assignable why this should
not be so, if we look upon the mesenchyme with its vessels and areolar tissue and cavernous
spaces as having been primarily derived from the embryonic body cavity.

The arrangement of the intestine as shown in sections of spat as small as that described
above is essentially the same as in the adult. The second bend of the intestine crosses the
gullet in the same way, but the double lateral longitudinal fold or tnduplicatiou is not so well
marked as in the intestine of the adult. The stomach is more nearly cylindrical and not so
ii -regular as in the adult. The contents of both the stomach and intestine show that diatoms
have formed a large proportion of the food of the young animal, in the sections of which, these
contents, in a number of my preparations, have been kept in situ.

The sections of the soft parts may be very readily double stained so as to bring out the
tissues of the reproductive organs very distinctly. To effect this, 1 throw the section into a
solution of methyl green for a few minutes, then into magenta, when it will be found that
the green will dye only the reproductive tissues, leaving the others scarcely tinged, while the red
will stain the mantle, liver, and connective tissues, mapping out these parts so distinctly as to
make a really useful as well as beautiful preparation.

Considerable care must be exercised in the preparation of the color solutions, so as not to
have them too intense. The sections should also be at once and quickly dehydrated or else the



758 NATURAL HISTORY OF AQUATIC ANIMALS.

alcohol will abstract the green and spoil in part the effect of the double stain. In making
sections, the best ones which I have ever made have been prepared from portions of whole
Oysters which had been imbedded iu paraffine, the latter substance having in the molten state
interpenetrated all the cavities and spaces in the hardened specimen, which had been previously
dehydrated and saturated with oil of turpentine.

Note on the organ of Bojanus of the Oyster. In the first part of this paper it is stated that the organ of Bojanus is
rudimentary or wanting in the Oyster. This statement must now be modified. Within the past year, M. Hoek, of
Leyden, has demonstrated the existence of the organ, of Bojanus in 0-ttrea edulis, and the writer has shown it to be present
in the American species as a crescent-shaped glandular or canaliculated structure lying just below the adductor and close
against it, as a paired organ which also extends slightly into the substance of the mantle on either side. JI. Hoek has
shown that, as in other acephalous mollusks, this organ communicates with the pericardiac cavity and the genital
openings. Its function is excretory.

Voices of the heart. A pair of very distinct valvular folds separates each of the auricles of the heart of the Oyster
from the ventricle, opening upward into the latter. They prevent the blood from regurgitating into the auricles, and
cause the blood-current to assume one constant direction, viz, from the auricles to the ventricles, and from the latter
through the anterior and posterior aortic vessels to the various parts of the body.

Fixation of the spat. Recent studies have led me .to the conclusion that the existence of a byssus in the fry of the
Oyster is very doubtful, and that fixation is accomplished at a very early stage, possibly twenty-four hours after the
embryos commence to swim, by the border of the mantle, as I have endeavored to show in my paper "On the Fixation of
the Fry of the Oyster," illustrated with figures, and recently prepared for the Bulletin of the United States Fish Com-
mission, where I also show that the beaks of the larval valves are constantly directed one way, and that the hinge end
of the larval shell is inclined upward, the free margin of the left larval valve being brought into close contact with the
surface to which attachment occurs through the instrumentality of the margin of the mantle. The attachment itself is a
very firm one, and consists of the horny matrix of the calcareous material which serves as a cement to glue the free
margin of the lower valve of the fry and spat to the surface which has been chosen as a permanent abode.



SECTION I.



PART V-CRUSTACEANS, WORMS, RADIATES, AND SPONGES.



By RICHARD RATHBUN.



759



ANALYSIS.



T. CRUSTACEANS :

221. The Crabs 763

222. The Common Edible or Blue Crab 775

->-':!. The Lobsters 780

224. The American Lobster 781

225. The Cray Fishes, Astucus and Cambarus 812

'226. The Shrimps and Prawns 816

227. The Mantis Shrimps: Squillidffl 823

228. The Amphipods 824

229. The laopods : 826

230. The Entomostracans 827

231. The Cirripedia 828

232. TheXiphosura 829

Z. WORMS :

233. The Annelids 831

234. The Leeches 833

Z. A. THE RADIATES :

235. The Echinoderms 838

236. The Coelenterates 841

Z. B. THE POHIFEKS :

237. The Sponges 843

238. The Genus Spongia, and the American Commercial Sponges 846

239. Injurious Sponges 860

(761)




Y. CRUSTACEANS.

221. THE CRABS.

Tin: Fmni.Kit CRABS GEL ASIMUS PUGNAX, Smith; GELABIMUS PUGILATOR, Latreille; GELASI-

MUS MINAX, Le Contc.

Three species of Fiddler Crabs occur upon the Atlantic const of the United States, and nre
frequently ut Mixed as liait. Congregating together in immense numbers, as they often do, and
excavating their holes generally in convenient localities, above the reach of the tides, they might
In- easily collected in large quantities, were they better appreciated by the fishermen. Most
dwellers upon the sea-shore are acquainted with that peculiarity of the Fiddler Crabs which has
given to them their common name, and by which they are readily distinguished from our other
Crabs. The males are provided with two very unequal claws, one being of large, the other of
quite small sixe. in comparison with the size of the animal. Of these, the larger claw has been
likened to a fiddle and the smaller one to a bow; hence the derivation of the name. The claws of
the females are, however, of equal ami small size.

The three species mentioned as living upon the Atlantic coast are Geltuimus minax, Q.
ptigniu; and G.piti/ihitnr. The former species, which is the largest, ranges from the southern coast
of New Kii^land to Florida, and lives upon salt marshes, usually farther from the sea than the
others, and frequently where the water is nearly fresh. G. piiynajr ranges from Cape Cod to
Florida, and also occurs in the (lull of Mexico and ninong the West Indies. "It makes its
burrows only upon salt marshes, I ut is often seen in great companies wandering out upon muddy
or sandy flats, or even upon the benches of the bays and sounds." G. puyilator ranges from Cape
Cod to Florida, upon muddy and sandy flats and beaches. Professor Verrill describes the habits
and characteristics of these species as follows: '

"We find several species of Crabs burrowing in muddy banks along the shores of the
estuaries, as well as along banks of the streams and ditches of the salt marshes. The most
abundant of these is the marsh Fiddler Crab, Gtlaaimus jrugnax, which is often so abundant that
the banks are completely honeycombed and undermined by them. These holes are of various
sizes up to about three-quarters of an inch in diameter, and descend more or less (>erpendicularly,
often to the depth of two feet or more. Occasionally in summer these Crabs will leave their holes
and scatter over the surface of the marshes, which at times seem to be perfectly alive with them,
but when disturbed they will scamper away in every direction and speedily retreat to their holes;
but occasionally, at least, they do not find their own, for sometimes the rightful owner will be seen
forcibly ejecting several intruders. It is probable that at such times of general retreat each one
gets into the first hole that he can find. Associated with this ' Fiddler,' another related Crab, the
Semrma reticulata, is occasionally found in considerable numbers. This is a stout-looking, reddish-
brown crab, with a squarish carapax ; its large claws are stout and nearly equal in both sexes,
instead of being very unequal, as in the male ' Fiddlers.' It lives in holes like the Fiddlers,'

'Heport upon the Invertebrate Animals of Vineyard Sound, etc., in Keport United States Fish Commissioner for
1P71-'T2, pp. 336, 466.

73



7(54 NATURAL HISTORY OF AQUATIC ANIMALS.

but its holes are usually much larger, often an inch or an inch and a half in diameter. It is much
less active than the ' Fiddlers,' but can pinch very powerfully with its large claws, which are
always promptly used when an opportunity occurs.

"On the marshes farther up the estuaries, and along the mouths of rivers and brooks, and
extending up even to places where the water is quite fresh, another and much larger species of
'Fiddler Crab' occurs, often in abundance; this is the Gelasimus mincuc. It can be easily
distinguished by its much larger size and by having a patch of red at the joints of the legs. Its
habits have been carefully studied by Mr. T. M. P-raddeu, of New Haven, who has also investigated
its anatomy. According to Mr. Prudden, this species, like Gelasimus puyilator, is a vegetarian.
He often saw it engaged in scraping up and eating a minute green algoid plant which covers the
surface of the mud. The male uses its small claw exclusively in obtaining its food and conveying
it to the month. The female uses either of her small ones indifferently. In enlarging its burrows,
Mr. Prudden observed that these Crabs scraped off the mud from the inside of the burrow by
means of the claws of the ambulatory legs, and, having formed the mud into a pellet, pushed it up
out of the hole by means of the elbow-like joint at the base of the great claw, when this is folded
down. He also ascertained that this Crab often constructs a regular oven-like arch of mud over
the month of its burrow. This archway is horizontal, and large and long enough to contain the
Crab, who quietly sits in this curious doorway on the -lookout for his enemies of all kinds.

" This species can live out of water and without food for many days. It can also live in
perfectly fresh water. One large male was kept in my laboratory in a glass jar, containing nothing
but a little siliceous sand moistened with pure, fresh water, for over six months. During this
whole period he seemed to be constantly in motion, walking round and round the jar and trying
to climb out. He was never observed to rest or appear tired, and after months of confinement and
starvation was just as pugnacious as ever.

"Although some of the colonies of this species live nearly or quite up to fresh water, others
are found farther down on the marshes, where the water is quite brackish, and thus there is a
middle ground where this and G. pugnax occur together. This was found by Mr. Prudden to be
the case both on the marshes bordering West River and on those of Mill River, near New Haven.
They are abundant along both these streams. The holes made by this species are much larger
than those of G. pugnax. Some of them are from an inch and a half to two inches in diameter.

" On sandy beaches near high-water mark, especially where the sand is rather compact and
somewhat sheltered, one of the ' Fiddler Crabs,' Gelasimus pugilator, is frequently found in great
numbers, either running actively about over the sand, or peering cautiously from their holes,
which are often thickly scattered over considerable areas. These holes are mostly from half an
inch to an inch in diameter, and a foot or more in depth, the upper part nearly perpendicular,
becoming horizontal below, with a chamber at the end. Mr. Smith, by lying perfectly still for
some time on the sand, succeeded in witnessing their mode of digging. In doing this they drag



Online LibraryG. Brown (George Brown) GoodeThe fisheries and fishery industries of the United States (Volume 1:1) → online text (page 126 of 146)