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FISHERY BOARD FOR SCOTLAND.
[SCIENTIFIC INVESTIGATIONS.
LIGeLO::
No. I.
REPORT ON THE REPRODUCTIVE ORGANS OF
SPARUS CENTRODONTUS, Delaroche; SPARUS
CANTHARUS, L.; SEBASTES MARINUS (1.);
AND SEBASTES DACTYLOPTERUS (Delaroche) ;
AND ON THE RIPE EGGS AND LARVAL OF
SPARUS CENTRODONTUS (?), AND SEBASTES
MARINUS
(wir 5 Puarss).
BY
H. C. WILLIAMSON, M.A., D.Sc, F.R.S.E.
This Paper may be referred to as:
‘* Fisheries, Scotland, Sct. Invest., 1910, I. (Sept. 1911).”
TON DON:
PUBLISHED BY HIS MAJESTY’S STATIONERY OFFICE.
To be purchased, either directly or through any Bookseller, from
OLIVER & BOYD, Tweeppate Court, EpinsurGH ; or
WYMAN & SONS, Lrp., Ferrer Lane, E.C.; or
E. PONSONBY, Lrp., 116 Grarron Srreetr, Dustin.
PRINTED BY
JAMES HEDDERWICK & SONS, LTD.,
Av ‘“‘THE CrTizEN Press,” Sr. Vincent PLACE, GLAscow.
One:
Price One Shilling and Sixpence.
FISHERY BOARD FOR SCOTLAND.
ON THE REPRODUCTIVE ORGANS OF SPARUS CENT RODON-
TUS, Delaroche; SPARUS CANTHARUS, L.; SEBASTES
MARINUS (L.); AND SHBASTES DACTYLOPTERUS
(Delaroche) ; AND ON THE RIPE EGGS AND LARVA
OF SPARUS CENTRODONTUS (?), AND SEBASTES
MARINUS.
BY
H. CHAS. WILLIAMSON, M.A., D.Sc, F.R.S-E..
MARINE LABORATORY, ABERDEEN.
(Plates I.-V.)
Sparus centrodontus, Delaroche.
This species, Cuvier and Valenciennes* state, was named by
Delaroche Sparus ecentrodontus. According to the French authors,
there is doubt as to the identity of the fish named Sparus orphus, L.
Dayt gives the name Sparus orphus, Lacép, as a synonym of Sparus
centrodontus, Delaroche. Cuvier and Valenciennes proposed to change
the name to Pagellus centrodontus. But there is, in my opinion, no
necessity for removing this species and Sparus cantharus, L., from the
genus Sparus.
This species is landed at Aberdeen by trawlers during the greater
part of the year. In September, 1910, it was being captured in
especially large quantities.
It is known as the Jerusalem Haddock, Bream, Silver Haddie
(Loch Tyne).
A description of this fish is given below.
Specimens{ have been examined during each month of the year for
the purpose of studying the development of the reproductive organs.
In no instance was the ovary ripe. It seems probable that when
spawning these fishes may retire to places where they are not taken
by the trawl.
The Reproductive Organs.
This species is hermaphrodite. A pair of testes and a pair of
ovaries are present in each fish, but the testis and ovary are not
always functioning simultaneously. ‘The testis and ovary are
intimately combined on each side of the fish.
* Cuvier et Valenciennes—‘‘ Histoire Naturelle des Poissons.” T. vi. Paris,
1829.
+ Day—‘‘The Fishes of Great Britain and Ireland.” 2 vols. London,
1880-1884.
t Mr. Eunson, fish merchant, Aberdeen, has very kindly given me most of the
examples of this and the other species dealt with in this paper.
(4116) Wt. 403/46—500—9/1911,
4 Fishery Board for Scotland.
While in some fishes both the testis and the ovary may be found
developing, in others only the testis or the ovary is developing. In
the latter case the portion of the organ belonging to the other sex
may be so small that it may escape notice ; but, so far as my experience
goes, it is present. All are potential hermaphrodites, but only a
proportion are functional hermaphrodites.
The fishes have been arranged in the table in the following classes :—
(1) predominant males, (2) predominant females, and (3) sexes equal.
The predominant male or female indicates that the testis or the ovary
is large, while the organ of the opposite sex is very small. The
number examined during each month, with their range of length, 1s
given. The length of the fish is the distance from the anterior tip of
the snout to the extremity of the longer tail ramus.
The range in size of the ova found in the fishes is entered in the
last column.
A number of the fishes were spents.
The fishes entered opposite each month do not all belong to the
same year. The observations were carried on over a period of three
and a half years.
SPENTS.
PREDOMI- PREDOMI-
NATING NATING Equal ; j
MALE. FEMALE. Ty Predominat- Predominat-| *Range of Size of
MOonru. ing Male. ing Female.j the Ovarian Ova.
Diaineter in mm.
5 By 3 he uni Be || ee S|
=| b: [2 2| es 12] es |S] we
B| 88 | 5 EB) g8 78] 38 | 8) ge
Z| & Z Z| = Z| = z | =
vans 2 |e si 2¥/ | | BRI || BY 7 | 32-3 Sy :
Feb. 3 34-43 |) 35, 5 32-34 J1(?) 37 Ps =<
March 1 37 2B) + 38F Bh 2) Small. oe ae
April af ar 1} 38 *¢ er. v 55
May 9 | 34-47 | 14 33-48 | 1 | 33 is ai
June 6 | 32-36 9 4 1 36 1 38
July 9 34-43 | 32 6 39-39 3 34-39 3 39-45
Aug. 8 34 43 2 BB Apa Bae es oe ec
Sept. 36 | 34-50 7 | 31-40] 5) 37-46) 4] 39-46
Oct. 10 | 32-44 1 34 : Me Ts)
Novy. 8 | 34-46 il kt 3 "06; “172 nabs
Dec. 2) 34,35 5 | 35-37 12-92, *95, °3.
*The sizes given include all the samples from all the groups that were measured during the month.
Sample eggs from every ovary were not measured. But the ovaries were examined for any indication
of ripening ; it is not therefore likely that in any of the fishes there were eggs of greater diameter than
“45 mm.
Out of 404 fishes, 38, measuring from 31 to 40 em., had the sexes
equal, while 128 predominant males measured from 31 to 50 em., and
238 predominant females measured from 32 to 49 cm. It may be
noted that the fishes having the sexes equal did not appear among the
specially large individuals.
A number of reproductive organs were obtained from a collection
of fishes captured off the west coast of Orkney in January.
The hermaphrodite condition is indicated when a testis and
an ovary are combined in one organ, ‘They may be of equal
size, as, for example, in Fig. 21, or the testis or the ovary may be much
the larger, as, for example, in Figs. 3a and 19 respectively. In the
latter division the very small sexual organ seems to be quite normal,
and is, I consider, functional. These are the conditions where the
sexual organs are not specially large, ¢.c., in small bream (e.g., Figs.
3a, 9, 19, 38, which are of natural size). But when one sex pre-
Reproductive Organs of Sparus Centrodontus. 5
dominates in the reproductive organ of a big Centrodontus, the other
sexual organ is so much reduced as hardly to be recognised ; it seems,
indeed, to be exhausted. This condition is seen in Fig. 40 (natural
size), where, while the ovary is large, the testis is reduced to a thread.
In the previous case the fishes were, I think, preparing to spawn for
the first time. In the latter case the ovary had been ripe before.
The conclusion, then, is that the organ when it first ripens is
hermaphrodite ; at the next spawning it may be unisexual. I do not
know whether the hermaphrodite condition may persist in the second
spawning. It seems not improbable that where in the hermaphrodite
condition one sex specially predominates, that will be the sole function-
ing sex at the next spawning.
Organs in which two sexes were equally represented are given in
Figs. 17 and 21. The testis was white, ripe. It was possible to make
out the heads of the sperms, but not their tails. The ovary had an
amber tinge. In one specimen, Fig. 21, the eggs measured up to
‘Imm. in diameter, while in the other they reached a diameter of
‘15mm. A section of the latter reproductive organ is given in Fig. 18.
Where the male predominated the testes were nearly all large and
white. In one case the testis was ripe. It was pasty in consistency ;
the heads of the sperms, but not their tails, were made out. The ovary
was very small and colourless ; it was enclosed in a deep groove in the
edge of the testis. The ovary was 4mm. broad, and it was sunk flush,
almost out of sight. In Fig. da the groove has been opened out to
expose the ovary (ov.). It is quite a normal immature ovary, with
ridges filled with minute eggs, measuring about ‘05mm. in diameter.
In another fish the ovary was only partly sunk in the groove (Fig. 9).
The eggs measured from -05mm.—"07mm., in diameter. They were
colourless, non-yolked, and clear. These ova have a distinct round
nucleus.
Sometimes the ova ‘05mm. in diameter, although translucent, are
not perfectly clear, as the substance of the egg is granular; they have
an exhausted appearance.
The dorsal mesentery (dm., Fig. 38), which supports the organ to
the roof of the abdominal cavity, runs along the ovary. The testis
forms the free ventral border of the united organ. Sometimes the
side of the ovary is attached to the testis; in other cases the attach-
ment is very slight (e.y., Fig. 25).
A section across a predominating male organ, at a quarter of its
leneth from its posterior extremity, is shown in Fig. 8. The ovary is
a sac, on the inside wall of which are arranged ridges filled with ova.
The ridges run longitudinally. In some cases, ¢.g., in a fish 43°5cm.
long, the egg-ridges rose little, if any, above the ‘surface of the ovary.
The eggs were clear and nucleated, the largest measuring ‘06mm. in
diameter. Part of the inside wall of the ovary is without ova, 7.e., the
oviducal part.
The ovary and the testis do not communicate. Between the two
there is a layer of lacunar, or spongy honeycomb tissue, which extends
into the wall of the ovary (sp., Fig. 8). This lacunar tissue acts as the
vas deferens.
The testis is of an honeycomb structure. A surface view ofa portion
of the ripe testis is shown in Fig. 16. It is seen from the outside.
The spaces are occupied with sperms. The internal structure of a
whitish developing testis consists essentially of tubules (¢f, Fig. 11).
6 Fishery Board for Scotland.
This drawing represents a transverse section of a portion of a testis.
The tubules, which are arranged in a columnar form, are in some
cases branched, and they appear to connect directly with the series of
ducts occupying the core of the lobe. Each tubule is enclosed at the
surface of the testis in a loculus formed by partitions arising from the
outside wall (sk., Fig. 10). The skin of the testis when torn tends to
split longitudinally. |
Some testes were mottled. The yellow mottling is seen in the core
of the testis (mt., Fig. 24). May this mottling indicate that the fish
has spawned before ?
The egg-ridges vanish in the posterior part of the ovary, which
becomes the plain-walled oviduct (Fig. 59). This figure represents a
view of the two organs in a predominating female. The ovaries are
large, and the testes (7’) are very small. On the side of the ovary next
the wall of the abdomen there is a digitiform region of the wall of the
ovary without egg-ridges. It is the oviduct (ovd.).
The testes do not unite.
The general arrangement of the organs in the abdomen of a
predominating male is shown in Fig. 6. The external aperture of
the vas deferens is omitted.
A series of transverse sections, not drawn to scale, illustrate the
arrangement of the parts. Fig. 24 is a section of a functional male
organ near its anterior end. The ovary has only a small attachment
to the testis. A section made near the Junction of the ovaries exhibits
a similar condition (Fig. 25). Large lacune are visible in the wall of
the ovary. Egg-ridges are present, but not on the portion of the wall
next the lacune. In a section further posteriorly, but where the
ovaries are still separate (Fig. 26), the lacunar tissue in the wall of the
ovary is very extensive. Ova are present on part of the wall of the
ovary. The testis had already ended at this point. A small lobe was,
however, found in a section of the single oviduct (Fig. 27) posterior
to the union of the ovaries. The junction of the ovaries is shown in
Fig. 28. In the section of the oviduct (Fig. 27), the lacunar tissue in
its wall represents the two vasa deferentia, which it was not possible
to separate. The lacunar tissue is apparently present throughout all
the wall of the oviduct. Further posteriorly the lacunar tissue is very
much increased (Fig. 32). It is present in the whole of the wall of
the oviduct, the mesentery forming a break or division. The lacunar
tissue was broader on one side than on the other, but that may be
simply due to unequal contraction. The strands which form the net-
work of the lacunar cavities appear to be muscular. A surface view
of the inside of the last portion of the oviduct is shown in Fig. 35, .
The duct has been slit open along its dorsal (7.e., posterior) side. The
lacunar tissue can be seen in parts through the lining skin of the
oviduct. It has a different appearance in different parts.
Near the end of the oviduct the lacunar tissue (la.) forms very
large cavities (Fig. 33) on the dorsal side, and in a section made close
to the external aperture, 7.¢., next the ventral wall of the abdomen,
spaces are seen to have grown into a definite tube on the dorsal edge,
the vas deferens (VD., Fig. 34). The posterior mesentery cuts the
lacunar tissue into two.
The further relationship of the parts is shown in a longitudinal
section through the cloacal region (Fig. 31). It is shown upside down.
The lacunar tissue on the posterior side is seen to open out into a
Reproductive Organs of Sparus Centrodontus. 7
wide vas deferens, which finds exit on the top of the urogenital papilla.
The opening of the vas deferens is immediately in front of that of the
urethra (wrth.), the two apertures being separated by a thin, soft
septum. On the anterior side the outer and inner skins of the
oviduct wall join together to close the lacunar space, which com-
municates round the neck of the oviduct.
On the end of the urethra there is a bulbous gland-like swelling.
When the papilla (pap., Fig. 29) is examined from the outside, the
single crater in its tip is seen to be divided by a transverse septum.
The papilla is not large; it is larger in the male than in the
female; sometimes it is inconspicuous. It is well supphed with
blood, and is formed of very fine spongy tissue. The sides of the
crater are sometimes soft and gauzy ; this condition makes it difficult
to separate the two small apertures.
The oviduct (ovd., Figs. 29, 31) opens in front of the vas deferens,
between it and the anus. The aperture appears to be partly closed
sometimes by the cohesion of its soft lips. The urogenital papilla
and the anal and oviduct apertures are sunk in the cloacal slit. The
slit is longitudinal and it closes neatly.
When the female sex predominated the ovary was large, and pink in
colour. The testis was small, in some cases so reduced as to be hardly
visible. The ova, when “3mm in diameter, were just visible to the
naked eye. When magnified they were opaque, and were enclosed in
a swollen follicle (Fig. 20). Some eggs from another ovary
measuring ‘*3mm in diameter were not quite opaque. The nucleus
(germinal vesicle) was visible, and it was pigmented. Eggs which
are storing up yolk have orange-coloured pigment in them. The
pigment is located in the nucleus as a rim of oily opaque corpuscles
(pi., Fig. 44). The size of the germinal vesicle varies (cp. Fig. 51).
It is possible that it has the power of expanding and contracting.
‘The clear eggs measured ‘15mm. in diameter. A few specks of red
colouring matter were made out in some clear eggs of that size.
The general arrangement of the organs in the abdominal cavity is
shown in Fig. 2. The ovary was large and orange-coloured. ‘The
testis (7') was rendered visible by some brown mottling along its
extent. The colouring matter is in little traces as well as in com-
paratively big patches.
A fine yellow mottling is to be seen scattered through some of the
ovaries. The ovarian ridges on the oviduct region of the ovary are
covered with a delicate cuticle, which can be easily dissected off in a
piece.
The mesentery (dm., Fig. 40) attaches the ovary to the swim-bladder.
The principal blood-vessel is situated on the side facing the other ovary.
The ovaries unite posteriorly, and end shortly thereafter. The
longitudinal egg-ridges, seen in section, tend to radiate from the large
blood-vessels. On the ridges are developed blunt villiform processes
full of ova. A developing ovary, which had been a spent, is
shown in Fig. 40. The testis, which is a very narrow fold, is in some
parts flush with the skin of the ovary. It could be traced right up to
the anterior end of the organ. The oviduct region (ovd.) is well
marked. In some cases, however, the testis began some distance short
of the anterior end of the ovary (cp. Fig. 22).
The testis is sometimes hardly visible; that appears to be the case
especially in ovaries that have been ripe before. The testis in Figs.
8 Fishery Board for Scotland.
19 and 38, although small, is functional and readily seen, while in
Pig. 40 the testis is so much reduced as to be probably non- functional, ;
and might be easily passed over. In the last ovary old egg- -capsules
were present, the remains of a previous spawning. The two classes of
reproductive organs differ also in the amount of empty space in the
early developing ovary (cp. Figs. 42 and 45).
Three sections were made across the organ shown in Fig. 40, viz.,
at the points A, B, and C. ‘The point “A is near the anterior ex-
tremity: the section is given in Fig. 45. The testis is visible as a
little projecting fold: the oviduct is absent. No part of the wall of
the ovary is free from eggs, but the ridges are narrow on the dorsal
and ventral sides. In a section at B, viz., across the beginning of the
oviduct, Fig. 46, the oviducal part is very narrow internally ; there is
little, if any, clear space. The testis is flush with the outer ‘skin. The
ovary has a big lumen. In the posterior part of the ovary at CO, the
oviduct is broader ; the testis is a little fold (Fig. 47). Near the union
of the ovaries, ae at D, the outside breadth of the oviduct is not
equalled by plain surface on the inside. The plain surface of the
oviduct inside an ovary is shown in Fig. 23. It exhibits a quantity
of minute white granules, which are thickly arranged about the
middle and gradually get fewer towards the egg-ridges at the sides.
Minute muscle-fibres are visible in the wall.
In the small ovary, Fig. 38, which is probably ripening for the first
time, the oviduct can be traced further anteriorly than in Fig. 40 (cp.
the cross sections, Figs. 42 and 43).
A section across the union of the ovaries of another fish shows the
posterior end of the septum (Fig. 49). In this case the testes were
dorso-lateral in position, while in another example they were ventro-
laterally placed. At a short distance posterior to the above point,
Fig. 50, the wall of the oviduct was spongy, thick, extensile, all round
except at the ventral region. The testis was pr esent on one side only.
The oviduct is wider than in the male. On the last part of the
oviduct I observed two lacunar areas, one bigger than the other, with
intervening plain areas, which exhibited straight longitudinal fibres.
The external opening of the oviduct is large; the lips are some-
times broad and leaf-like.
The urogenital papilla in the female is small. The opening on its
tip is crater-like, and on first examination it appears to be a single
aperture. But if a section be made across the papilla the two ducts
are found. The urethra has a thick wall, and its lumen diminishes
somewhat near the aperture. The vas deferens is a slit which is
closed (Fig. 41). The two ducts meet just at the aperture. The
papilla is formed of spongy material.
It is an interesting problem whether a fish which becomes unisexual
will remain always of that sex. It seems probable that it will do so,
for in several developing predominant females I have found the old
capsules of ripe eggs which had been retained in the spent ovary.
(Vide also p. 10.)
Notes on the Reproductwe Organs.
The stage of development of the ovary in the fishes examined in
each month is indicated by the size of the eggs entered in the last
column of the table on page 4.
Reproductive Organs of Sparus Centrodontus. 9
In January, February. March and May some of the testes were ripe.
In June, July, and August, while there were small ovaries and
testes, some spent ovaries were found.
In September the fishes presented large and small testes, developing
ovaries, and spent ovaries and testes.
In October the testes and ovaries were small and developing; one
ovary was spent.
In November fairly large testes and ovary were found. The fishes
had much abdominal fat.
In December a small testis was growing white; an ovary was
developing. A considerable quantity of abdominal fat was present.
The Ripe Kggs.
No ripe ovary was obtained, but in several fishes the old capsules
of ripe eggs were still present. The eggs were crushed and dried.
Only a little white amorphous matter remained inside. An opaque
circular mass, sometimes stained yellow, could be detected in the
amorphous material. The yellowish mass measured about ‘27 and ‘3
mm. in diameter. In two cases when the egg was dissected a little
white coherent irregular body, measuring about 2 mm. in diameter,
was found. This, I think, may be the remains of an oil globule. In
September a quantity of unspawned crushed ova remained in an ovary.
A bright golden oil globule was present in the ege. In one it
measured *25 mm. in diameter.
The crushed capsules were oval and the eggs had evidently been
oval. Several of these capsules were measured; the sizes were as
follows: —1°35 x°8, 1:°2x°75, 1:2x-75, 1:2x°75, 1:1x-9, 10x89.
1:0 x ‘7 mm.
Undeseribed Pelagic Fish Egg.
An egg which appeared in the surface tow-net collections made in
1903 by the Fishery Board, in connection with the International
Investigation of the North Sea, was remarkable in that it was oval in
shape and had an oil globule (Fig. 13).
The eggs were measured after preservation in formaline solution.
The oil globule varied from ‘17 to ‘12 mm. in diameter. The following
are the sizes of the eggs in which the oil globule measured ‘17, alo
‘12mm. respectively :—Oil globule -17 mm.—eggs, 1-4 x PP2E 37 Xx
11, 1°32 1:17, 1:31:05 mm. Oil globule 15 mm.—eggs, 1°37 x 1+1,
1°35 x 1-2, 1°35 x 1-07, 1-35 x 1:05, 1:32 x 1-1, 1:32 x 1-07, 1:32 x 1-05,
1°3 x 1:07, 1-27 x 1:1, 1:25 x 1:1. 1:25 x 1:07mm. Oil globule -12mm.—
egg, 1°35 x 1:1 mm.
I consider that this egg is that of Sparus centrodontus. It was cap-
tured in May at points about 40 miles east and 15 to 20 miles west
of Shetland respectively. The embryos were all early, except one
which extended for about two-thirds round the yolk. One egg was
obtained in June, about 20 miles west of Shetland. The embryo was
in the disc stage. In August a large number, 84 in all, was obtained
off Kinnaird Head, Moray Firth. The exact position was—Troup
Head, S.W. by W.; Kinnaird Head, S.E.3S. The eggs were all
recently spawned, the embryo being in the disc stage. A very deep
hole (100 fms.) occurs in this vicinity, about six miles off-shore,
10 Fishery Board for Seotland.
During the same month one egg was got between Orkney and Shet-
land, viz., ten miles E. of Fair Isle. The embryo was about three-
quarters developed. Thirty-eight eges were captured 40 miles E. of
Shetland in this month. The embryos were about ready to hatch
(Fig. 5). The embryo dissected out of one of the eggs is shown
enlarged in Fig. 12.
Almormal Reproductive Organs.
A fish measuring 47 cm. in length had a normal reproductive organ
on the left side (/.) and an abnormal organ on the right side (Fig. 1).
The latter contained several dark-coloured concretions(c.), while a small
concretion (¢’) was attached to the testis of the left organ. The
concretions are collections of unspawned eggs. The concretion ¢”' is
hard and dark-coloured. It is situated in the ovary. It cuts like a
hard cheese, and shows in section a conglomerate of eggs. The eggs
in the lighter-coloured balls, ¢. and ¢’, appear to be formed of the eggs
of a later spawning than ec”.
The quashed eggs measured 1:5 mm. in greatest length. The cap-
sules were flattened and the yolk had disappeared from many alto-
gether, abhoueh still present in some. ‘The old eggs had a single oil
globule :22 mm. in diameter.
The nate comb structure of the testis was well seen in the right
organ. Clean oval holes were observed in the septa of the honeycomb
tissue.
The lett ovary was developing, while the other remained in a state
of quiescence. The presence of the ball of unspawned eggs had eyvi-
dently inhibited the development of a new crop of ova. Will the for-
mation of the new ova be prevented if the ovary is in a state of com-
pression ?
In another fish the anterior portion of the ovary was detached from
the remainder (Fig. 19). No testis was observed attached to the isolated
portion.
A Mish with a Second Anus.
A fish which measured 42 cm. in length had a second anus. ‘The
gut was attached to the wall of the abdomen, which was perforated by
a pore that opened into the gut (Fig. 3).
The usual condition of the gut is as follows :—After leaving the
stomach the gut (d) passes back to the end of the abdominal cavity ;
it then turns round and comes forward to the anterior end of the
cavity. It then returns posteriorly and proceeds directly to the anus.
The three portions of the gut are looped together by mesentery. The
middle portion of the gut is the part which was connected to the second
anus (av). An enlarged drawing, Fig. 7, shows the gut and the part
of the abdominal wall (1). A fat-fold is attached to the mesentery.
Two encysted parasites (c) were located in the mesentery. The con-
tinuation of the gut through the body wall is shown in Fig. 15. The
antero-posterior direction is indicated by the letters a—-p. The
secondary anus was 2mm. long. ‘Two little processes were present on
one side (Fig. 14).
It seemed as if very little matter could have found exit by this
aperture.
Reproductive Organs of Sparus Centrodontus. 11
DESCRIPTION OF Sparus centrodontus, Delaroche.
This fish is coloured a bright red or pink. Over the abdomen there
is a golden red sheen. Small specimens show little red on the body ;
they are more silvery. The snout, cheeks, and sides are silvery with a
golden tinge. A prominent black patch is present on the shoulder,
on the beginning of the lateral line. The lateral line is prominent.
The dorsum has a metallic appearance. The top of the head is
pinkish. The inside of the mouth, and the inside surface of the gilJ-
cover, are pink and orange-red respectively.
The scales are ctenoid (Fig. 60); they are large and hard. The general
arrangement of the scales is indicated in the drawing Fig. 4; the
scales themselves are represented diagrammatically. ‘The scales are
arranged in parallel rows. This gives rise to the longitudinal rows
(or lineation) which are made out on the side of the fish. The large
semi-circular scale situated immediately over the opercular cleft is note-
worthy. Alongside the base of the ventral fin one or two scales are
elongated into a sharp triangular form, which resembles a short spine.
The scales are, however, thin and flexible. On the ventral surface
the scales between the ventral fins are extended posteriorly in a
triangular projection.
All the fins are red. The exact number of fin-rays is not entered
in the drawing. The number of fin-rays in the dorsal and anal fins
is shown in the following table :—
[
Dorsal. Anal.
Length
of Fish. a4 Soft A AS Soft
PCE Te Raye. SPMes hRaws
em. E
36 (25 | Fin-rays). 3 3
37 Aiea 42 z 18
Boe Wil 18 3 15
42 toes | 12 3 | D
4,2 12 | 15 3 | 3 |
45 12 13 3 Pein |
46 12 13 3 Ae
The dorsal fin is composed of spines and soft rays. Of the former
there are usually 12, and of the latter 15. The first of the soft rays
ends in a single tip as a rule; in one fish the tip was split. The
remaining soft rays are split. The dorsal fin stands in a groove in
the dorsal edge of the body. The front halt of the fin, consisting of
the spinous rays, can be laid down into the groove. The last two
rays are close together at their bases. The first two spines and the
last two rays arise from a single interspinous line in each case. The
lip of the hind portion of the groove is formed by large thin scales
which rise up from the dorsal edge on each side of the fin. The
scales are continued upon the bases of the last two rays as a process
similar to that shown for Cantharus in Fig. 113.
12 Fishery Board for Scotland.
The anal fin, like the dorsal, stands in a groove, the lip of which is
formed posteriorly of scales which are continued in a process upon
the proximal part of the last tworays. The first three rays are spines.
The last two rays are close together at their bases. The first two
spines and the last two rays arise from a single interspinous bone in
each case. ‘l'he angle between the last ray of the dorsal and anal fins
respectively and the edge of the body is not filled up with a
membrane.
The pectoral fin has 16 rays.
The ventral fin has 6 rays; the first of these is a spine. Only a
very small portion of the angle between the last ray and the ventral
surface of the body is filled up with a membrane.
The anus and the apertures of the genital organs and urethra are
in a slit-like depression on the ventral edge—the cloacal slit. It is
indicated at a.
The teeth in a centrodontus 40 cm. in length were small. They were
of two distinct kinds. On the premaxille there were at the
symphysis about four rows of small curved sharp teeth. Posteriorly
there were three rows; of these three the outer row were tusk-like,
while the inside row consisted of rounded-topped molar-hke teeth.
In the lower jaw (Fig. 37) two rows of teeth were made out in the
dentary at the symphysis; the outer row of curved teeth, the mner
row of teeth with blunted tips. All the teeth were small, but the
outer row contained the largest. Posteriorly the inner row showed
the rounded molar-like teeth. .
The upper lip is papillated ; the papillee dip in between the teeth
of the outer row. The papillation occurs in the lower jaw only to a
slight extent.
Inside both upper and lower jaws there is a pouch formed by a
horizontal membrane joining the premaxille and dentaries respectively.
A longitudinal strip of red muscle is present on the side just
beneath the skin.
The peritoneum is black.
The urinary bladder is in a little chamber cut off from the end of the
abdominal cavity by a septum of peritoneum crossing the cavity
between the oviduct and the urinary bladder. The chamber is lined
with peritoneum. The urinary bladder is wide; it is sometimes
covered with a layer of fat. A mass of fat is sometimes found in the
posterior end of the abdominal cavity. The ureter (ur, Fig. 6)
comes down medianly in front of the first hamal spine, and crosses
over the left side of the swim-bladder to join the urinary bladder.
The swim-bladder is large. A thick yellow matter was found in
the hind end of the swim-bladder of a fish 46 em. long in November.
Posteriorly the swim-bladder is firmly attached to the first heemal
spine. The first heemal spine ends the abdominal cavity and also the
swim-bladder. The first and second hemal spines touch one another.
The interspinous bones are long (int., Fig. 2).
The number of vertebrae in one specimen was 23. The first heemal
arch was on the tenth vertebra.
Sparus cantharus, L.—The Black Bream.
This species is landed by trawlers at Aberdeen from time to time.
One example examined in November in the fresh condition measured
Reproductive Organs of Sparus Centrodontus. 13
40:5 cm. in length. It was a silvery fish, with a slight bluish tinge
on the dorsum. The cheeks were silvery. The top of the head was
of a purplish colour. The inside of the mouth and the inside surface
of the gill-cover were white.
The lateral line is prominent (Fig. 30). The scales, which are
ctenoid, are large, and are arranged in parallel rows. A series of
longitudinal rows is prominent. A golden sheen is observed in the
rows sometimes. The large semi-circular scale situated immediately
over the opercular cleft is noteworthy.
The mouth is small, with prominent lips; it resembles the mouth of
Labrus. The teeth are comparatively large. They cover a broad
area in the jaws (Fig. 36). There are at least six rows of teeth in the
front of the lower jaw. The outside row of teeth are the largest.
They are sharp-pointed. The teeth gradually decrease in size towards
the inside of the jaw. No round-topped molar tooth was made out.
There is in both jaws a pouch formed by a horizontal membrane
joined to the premaxille: and dentaries respectively.
A strip of red muscle is present along the middle of the side.
The peritoneum is white.
The urinary bladder is large. Its attachment in the hind end of
the abdominal cavity is median, but it extends forward on the right
side of the body in the form of a broad lobe. It reaches to the
rectum. It is very vascular.
No urogenital papilla was observed. The apertures of the urethra
and vas deferens were sunk in three cases examined.
All the fins are dusky in colour. The fins are composed of spines
and soft rays.
The dorsal fin is dark, but the web between the rays was blotched
with pink. There were 11 spines and 13 soft rays in this fin in three
cases, 10 spines and 14 soft rays in one case, and 11 spines and 12
soft rays in another case. The first of the soft rays had a very fine
stiff but flexible point. The last two fin-rays arise close together.
This fin stands in a groove. The first half of the fin can be laid
down and almost hidden in the groove. The hind part of the groove
has thin, soft edges formed of scales, and these run up on to the last
rays, in a free process (Fig. 113). A similar arrangement is present
in connection with the anal fin, but here there are two processes on
each side, one a little anterior to the other. The anal fin had 3 spines
and 11 soft rays in five cases. The first two spines arise from the
first interspinous bone. The last two rays arise close together from a
single interspinous bone. This fin had its base, both fin-rays and
web, whitish ; its distal half is blackish. In one fish the fin was
bluish. The anal fin, all but its last three rays, stands in a groove.
When the dorsal and anal fins are distended the spinous and soft-
rayed portions of the fins are not marked off from one another. The
fin has the appearance of a single fin, not of two fins joined
together.
The pectoral fin is almost colourless. It had 16 rays, and reached
to the level of the anus in one fish.
The ventral fin is dusky ; the rays were bluish in one. It had six
rays. The first ray is a spine. Alongside the base of this fin an
elongated but thin scale is present. At the ventral surface between
the ventral fins the scales project in a triangular process. In a fish
42 cm. long the dorsal ramus of the tail was the longer.
14 Fishery Board for Scotland.
The number of vertebree in three cases was 24. ‘The first hamal
spine was on the eleventh vertebra.
The otolith is convex on one side and concave on the other. Views
of both sides and also an edge view of the otolith are given in
Figs. 52, 53, and 54.
Comparison between Centrodontus and Cantharus.
The two species may be confounded. They resemble one another
in the general shape of the body. Ifthe upper jaws of Cantharus be
retracted and the mouth shut, a specimen of this species might be
taken for a pale-coloured example of Sparus centrodontus. Some-
times the smaller Centrodontus (e.g., 20 cm. long) show little red
colour, and they may be mistaken for Cantharus, i.e., when the colour
is taken as a guide.
The longitudinal rows are rather more marked in Cantharus. The
eyes of that species are smaller than those of Centrodontus.
Cantharus has a smaller mouth, and more and larger teeth, than
Centrodontus. They both have a prominent dorsal ridge in front of
the dorsal fin: that of Cantharus is the more acute. They differ in
the shape of the head, seen in profile. Centrodontus has a more
rounded and fuller snout, but the difference is not always easily
ganged.
Cantharus has less body thickness, from side to side, than Centro-
dontus.
The two species differ in the colour of the inside of the mouth, gill-
cover, and peritoneum ; vide pp. 11 and 13.
The Reproductive Organ of Sparus cantharus.
The reproductive organ resembles that of centrodontus ; it is herma-
phrodite. Ina fish 40°5 cm. long, a predominant female, the ovary was
orange-coloured. A little testis was present along the lower border
of the ovary. The ovarian folds filled up the ovary (Fig. 48). These
folds are composed of digitiform processes filled with eggs. The
organ does not appear to have been ripe before. The yolked eggs
measured *35 mm, in diameter. Most of the eggs were small and
clear. There was a slight pink sheen in the yolked eggs when they
were examined with the microscope. The egg filled the follicle
almost completely. There were little masses of opaque yellow
pigment throughout the ovary.
_ A fish 42 cm. long wasa predominant male. The testis was small
and mottled. It had, I think, been spent. The ovary was a wide
sac. Some small eggs were seen in the wall of the ovary. The
lacunar tissue in the wall of the ovary was very open. The external
aperture of the oviduct was closed. The urethra and vas deferens
opened by the same external pore. In a second predominant male,
39 cm. long, the ovary was a wide sac, and a quantity of yellow
glandular-like bodies projected from the internal surface. In the
anterior region they were located all round the ovary, but in the
remainder of the organ they were restricted in distribution; in
the posterior part they were merely dorsal in position. They were
arranged in a manner generally resembling the distribution of the
Reproductive Organs of Sparus Centrodontus. 15
ege-ridges, Small eggs are associated with these yellow bodies.
They are evidently the yellow giands that are seen in the developing
ovary.
The January fish 42cm. long had yolked eggs ‘37 mm. in diameter.
Sebastes marinus (1).
According to Cuvier and Valenciennes,* Linneeus included this fish,
and Perea seriba, L., under the name Perca marina, L. Miiller named
it Perea norvegica. The two French authors said that ‘its form is
nearly that of the Perch or of the large Serranus;” and further, ‘ it
is not a Perch, but a Sebastes similar to the form described by
Delaroche under the name NScorpena dactyloptera.” Cuvier and
Valenciennes gave it the name Sebastes norvegicus. Smitt, in
‘ Scandinavian Fishes,” uses the name Sebastes marinus (L.).
This fish is undoubtedly a Perca, It resembles Perea fluviatilis
very much in general shape, colouration, and external characters.
The chief difference lies in the dorsal fin, which is here a single long
fin having two distinct parts. In Perea fluviatilis these two parts are
separate fins. The exclusion of Sehastes marinus from the genus
Perca does not appear to me to have been justified. The question is,
however, complicated by the other members of the genus Sebastes,
and especially by Sebastes dactylopterus, which is described in another
part of this paper.
This fish, which is known as the Norway Haddock, or Runkie, is
landed regularly by trawlers at Aberdeen. Large quantities are
brought from Iceland, but some are also got in the North Sea.
Among the adult specimens examined there was a great difference
in size, so much so that there appeared the possibility that two species
were included under the same name. <A comparison which was
instituted between the two lots of fish revealed no structural differ-
ence of importance. ‘This question is referred to below.
The general external appearance of the fish is shown in Fig, 56
The exact number of fin-rays has not been introduced into each fin.
The fish is red or pink coloured externally. It exhibits a large
black blotch on the operculum, anda small blotch on the lower angles
of the operculum and sub-opereulum. Dark-ved or brown bars cross
the dorsum and extend down on to the side to a greater or less
extent. The bars are five in number. ‘The first is over the opercular
region, the second and third are under the spinous portion of the
dorsal fin. The fourth is under the soft-rayed portion of the
dorsal fin. The fifth is on the root of the tail. In the small
specimens the bars extended down to and past the lateral line; they
were of irregular shape, broadened out in one part and narrowing at
another. The fins are of a brilliant red; the lower half of the
pectoral fin and the ventral and anal fins are especially so. The
inside of the mouth and pharynx is white or pink-coloured. The
red colour gradually fades away after preservation. The black blotch
on the operculum is sometimes absent in some of the large fishes
landed (e.g., 38 cm. in length), and the bars can hardly be traced in
some examples; these fishes had probably been iced. The inside
surface of the operculum has a small amount of black pigment. The
teeth in the jaws are numerous and small. ‘Teeth are also present on
* “ Histoire Naturelle des Poissons,’ T. IV. Paris, 1829.
16 Fishery Board for Scotland.
the vomer and the palatine ridges. Horizontal membranes join inside
the mouth, the premaxille, and the dentaries respectively. The
number of fin-rays in the several fins is given below. The hind edge
of the tail fin is slightly concave. The dorsal and ventral edges of
the base of this fin form somewhat sharp ridges,
The lateral line is slightly bent.
The head is adorned externally by a number of teeth. In two
fishes, 48 and 49 cm. long, the teeth on the top of the head were
arranged as follows :—One tooth projected over the orbit. A ridge
over the top of the orbit ended posteriorly in a little tooth. Two
isolated teeth were found further back on nearly the same line. On
the head still further behind a prominent plain ridge runs backwards
and outwards on each side: it may end ina little tooth. Between
the ridges the top of the head is flat or very slightly hollowed. The
interorbital space is flat or slightly depressed. The teeth on the side
of the opercular bones, and at the beginning of the lateral line, are
indicated in the figure.
A marked feature in the appearance of the fish is the hump
immediately in front of the beginning of the dorsal fin. The lower
jaw is prominent.
The eye is large : the cornea is loose. The cornea is a translucent
portion of the skin of the head. The orbit is round.
The scales are ctenoid (Fig. 61). No attempt was made to intro-
duce the exact number or size of scales into the drawing (Fig. 56), but
their general distribution is indicated. The outside of the lower
jaw is covered with scales. They are well seen in large specimens,
e.g., 48 and 49 cm. in length. In small examples, e¢.g., 20 cm. long,
they were detected on the posterior half of the jaw only.
The peritoneum is black. The swim-bladder is large. The ureter
is median.
The pyloric ceca were 8 or 9 in number in both large and small
fishes (three specimens of each).
The first heemal spine is forked at its extremity (Fig. 97). The
angle varies in depth. The point of the first interspinous bone of the
anal fin enters and is bound to the fork of the first hemal spine.
The interspinous bone forms the hind border of the adominal cavity.
A comparison was instituted between 54 fishes measuring from
17-4 to 24 cm., and 4 Iceland fishes measuring 89 and 42 cm, in
length. The small fishes were, with two exceptions, pregnant
females. They showed the dark bars more prominently. The
characters selected for comparison were (a) the horizontal diameter
of the orbit, (b) the distance from the tip of the mandible—when the
mouth was closed—of the following points, viz., the beginning of the
pectoral, ventral, dorsal and tail fins, the anterior edge of the orbit
and opercular cleft. The numbers of fin-rays and vertebre were also a
basis for comparison. The fish was laid on a centimeter scale, and
the distances were marked off on the scale by means of a needle.
The distances are taken along the longitudinal axis of the fish.
Agreement was found in respect to the measurement characters
between the two lots of fishes except in three characters, viz.:—The
orbit in the smaller fishes was the larger. It measured in horizontal
diameter 9°2 to 11'3 per cent. of the length of the fish. The length
of the fish in this case is the distance from the tip of the mandible,
when the mouth is closed, to the end of the middle rays of the tail fin.
Reproductive Organs of Sparus Centrodontus. 17
In the Iceland fish the orbit was 7°6 to 85 per cent. of the length of
the fish. Then the distance from the tip of the mandible to the
anterior edge of the orbit was 5'7 to 7°3 per cent. of the length in the
small fishes, while in the large specimens it was from 8 to 8-7 per
cent. of the corresponding distance. The ventral ramus of the tail of
the Iceland specimens was a little longer than that of the small fishes.
Ido not think that these differences are of specific value.
The details of the measurements expressed in percentages of the
length of the fish are given in the following table. Certain measure-
ments were made on the Iceland fishes alone. They are included here,
as they may be useful for comparison with other specimens :—
| TABLE,
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Reproductive Organs of Sparus Centrodontus,
(ibs)
The details of the numbers of fin-rays and vertebree for the fishes,
small and large, in which the characters were noted are given in the
next table.
ENUMERATION CHARACTERS.—Numbers of Fin-Rays and Vertebre.
All the fishes 17°7-24'4 cm. in length, except those marked
thus (ft), were female, and mature.
Length.*
cm.
DorsaL Fin,
Spine
Rays.
15
15
15
15
15
|
|
Soft
Rays.
15
15
15
14
15
ANAL FIN.
Spine | Soft
Rays. | Rays.
GS ©9 OS OS Oo GO G9 Co GO OO OO Co Co Co GO OO CY Co OO GO CO OO CO Co CO Oe Co OO G2 Co OD Go Co Co Co OO OO to
OHO OM MDMODNDDNNDWOAODOONOnNWOOANDMOAOnNOO IMA A]SH 10 NOOO
PrecroraL FIN.
Thin
Rays.
t © 00 6 6O
9
10
© GC TO OH OH CO ©
|
|
Thick
Rays.
—
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.
S
~~
— —
enh cee a)
—
Vertebree
31
* The length is the distance from the tip of mandible, when the mouth is closed, to the
end of the longest ray of the tail fin,
+ Male fish,
+Sex not noted,
20 Fishery Board for Scotland.
ENUMERATION CHARACTERS—continued.
Dorsau FIN. ANAL Fn. PecroraL Fr.
Length.* r z Vertebree
Spine Soft Spine Soft Thin | Thick
ae Rays. Rays. Rays. | Rays. | Rays. | Rays.
20 15 14 3 8 9 8
20 15 14 3 7. 8 10
20 15 15 3 8 9 9
21 15 is 3 8 9 9
| 15 15 3 8 9 9 5g
it 1 15 3 8 8 10 30
21 15 15 3 8 8 10 30
21 1055 14 3 if 9 9 30
Za 15 15) 3 8 9 9 30
21 15 15 3 8 10 8 30
Dit 113) 15 3 7 9 9 -
21 15 15 3 8 8 10 30
22, 15) 15 3 ff 9 9 30
22 15 15 3 8 9 9 30
23 14 14 3 8 9 8 30
24°4 15 17 3 8 9 9 30
+36 iD 14 3 8) 10 8
37 15 14 3 8) 9 9 oes
738 15 17 3 9 10 9 3)
£39 15 AU) 3 8 31
£39 1B) 15 3 8 ob
+39 1 14 3 8 31
+42 15 15 3 8 31
$39 15 16 3 9 31
$40 15 iN 7 3 10 31
$42. 15 16 3 i) 31
$43 i WS) 15) 3) 9 31
§50 15 15 3 9 31
* The length is the distance from the tip of mandible, when the mouth is closed, to the
end of the longest ray of the tail fin.
+ Locality unknown. + Iceland fishes. § Probably from Iceland.
Two kinds of fin-rays, viz., spine-rays and soft rays, are present in
the dorsal, anal, and ventral fins.
The dorsal fin had from 28 to 32 rays. Of these, 15 were usually
spines, the remainder soft rays. The spines occupy the larger part of
the fin. The spinous portion of the fin is of a different breadth from
the soft-rayed portion. The spine-ray has membrane attached right
to the tip on its posterior edge. The bases of the two last soft rays
are close together and attached to a single interspinous bone
(Fig. 96a). The first two rays (spines) arise from a single interspinous
bone also.
The anal fin had 10 to 13 rays, of which three were spines. The
last two soft rays are close together and attached to a single inter-
spinous bone (Fig. 96). The first two spines arise from the first
interspinous bone.
Reproductive Organs of Sparus Centrodontus. 21
The angle between the last ray of the dorsal and anal fins and
the edge of the body is usually filled with a membrane (id., Fig. 98).
This membrane varies in its size, and is more usually noticeable in
the larger fishes. In the small fishes it is very slight.
The pectoral fin had 17 to 19 rays. The upper half of the fin is
composed of rays which have thin tips; the lower half of the fin is
composed of swollen rays, the tips of which are usually single and
slightly separated from one another. The last ray is sometimes thin,
and in one specimen it was branched. Most of the rays of the upper
half of the fin have two points. In one fish, of the 9 thin rays the
4th to 9th had split tips.
The ventral fin consists of one spine-ray and five soft rays. ‘The
spine-ray is tightly bound to the first soft ray. A membrane fills the
angle between the last soft ray and the surface of the abdomen.
The vertebrae numbered 30 and 31. Among the small fishes the
most frequent number of vertebrae was 30. In 15 fishes, measuring
from 38 to 50 em. in length, the number was 31.
The vertebra bearing the first heemal spine was in 9 fishes (19 to
21 cm. long) the 12th (total number, 30), while in the 15 larger fishes
it was the 13th.
Differences have been noted between large fishes. Some fishes are
not so deep nor so thick as others. Certain of these lighter fishes
which were landed in December and January probably came from
Icelandic waters. Six of them, measuring from 39 to 50 cm. in total
length were compared with a North Sea specimen (May) measuring
37 em. in length. The Iceland fishes were of a bright red;
the dark bars were hardly to be detected at all. The North Sea
fish hada larger eye, broader dorsal and anal fins, with, in each
case, larger and stouter spines, a deeper and thicker body, than
the other group. The latter had a bigger tail fin, and the hind
margin of that fin was rather more deeply concave than in the
North Sea fish. These characters were measured (in em.) on the
North Sea specimen and on an Iceland fish, and the results are shown
in the following table :—
Horizon-| Dorsal Fin. Anal Fin.
Length of tal | Tail Fin. pe
Fish. |Diameter|,, . ,, (Largest |;, . ,, [Largest| Least |Ventral
cm. of Orbit. Beene Spine. noes Spine. | Spread.| Ramus. Men
37 N. Sea 31 371 4°2 3°3 S03) 4°6 6°9 8°6
39 Iceland Bee 2k) 26 2°3 Sol | iGi9 | tee 87
The least spread of the tail was the breadth of the fin when it was
smoothed out, with each fin-ray close to its neighbour. The ventral
ramus of the tail was measured from the root of the tail, approximately
at the beginning of the outer rays.
The North Sea specimen was compared with two other fishes
measuring 48 and 50 cm. in length respectively, which had been landed
fresh and ungutted at Aberdeen ; they, no doubt, came from the North
Sea. In the 48cm. fish the dorsal fin was narrower and the spines
were not so stout as in the specimen 37cm. long. ‘The fish
50cm. long had the fin as broad and the spines about as stout as
in the deep fish.
bo
Fishery Board for Seotland.
bo
The differences were well marked; they may be racial. Both
varieties seem to exist in the North Sea. It is possible that two
species are included under the name Sebastes marinus, but, if that be
so, it is probably the case that both grow comparatively large.
Liitken* regarded Sebastes marinus and Sebastes viviparus as distinct
species. Smitt considered that the latter was merely a variety of the
former. Vanhoéffent was of the opinion that a specimen of Sebastes
marinus got at Greenland showed no important difference from
examples of Sebastes viviparus captured in the North Sea. Cuvier and
Valenciennes considered that forms of Sebastes from Norway and
Newfoundland did not differ.
The Fishes Examined.
In order to study the development of the reproductive organs,
specimens were examined during each month of the year.
In the following table an analysis of the fishes with respect to
sex, length, and the stage of development of the ovary is given for
each month. The length of the fish is the distance from the tip of the
mandible (when the mouth is closed) to the end of the longest ray of
the tail fin.
The investigation covered the period January, 1908, to November,
1910. Fishes examined in different years are included in the total for
the month.
In most cases the locality of capture is not known. In some cases
it is, no doubt, the North Sea.
* Smitt—‘‘ Scandinavian Fishes.’’ Stockholm, 1893.
+ ‘*Grondland Expedition der Gesellschaft fiir Erdkunde zu Berlin, 1891-
1893.” 3 Bd., 1 teil. Die Fische. Berlin, 1897.
TABLE
Reproductive Organs of Sparus Centrodontus. 25
Mate. FEMALE.
Monrtu. | Locatiry. es DEVELOPMENT OF
Range | Range of ETON ES
No. No 5
of Size. j | Size
cm. cnt.
January, - | Iceland | 18 345to 47) 25 | 34to 48 | Ova, ‘4 to1-Omm. in
| | | diameter.
February, - Unknown | il | 38to46) 6 23°5 to 46 | Ova, ‘8 and ‘9mm. in
| diameter.
March, - |Unknown| 20 | 35t045| 9) 36to45 | Ova, 10mm. in dia-
| meter.
March, - | Iceland il TA hice Aa
April, - (Unknown | 9 /|36t046| 5 | 38t050 | Ova, 1:12 to 14mm.
| in diam. Hggs free.
May, - ‘Unknown | t1 (Oe ter we
May, * 90 | 34to47| 34 | 24to50 | Free eggs in ovary.
| Spent and imma-
| | ture ovaries.
June, - North Sea] 2 |17-9,19°3) 47 | 17:7 to 24 | Ovaand larveefree in
ovary. Spentovaries.
June, - Unknown |{10 | 36to44; 5 | 38to42 | Larveeinovary. Spent.
Small ovary.
July, - |Unknown | 10 | 38to43| 7 | 38to50 | Spent.
July, - Unknown | ... sis 1 74 Spent.
August, Unknown | 8 | 35to45| 18 | 37 to 48 Spent ovaries, devel-
oping.
September, [Unknown 7 | 39to47| 5 | 41 to 49 | Spentovaries. Devel-
oping ovaries.
October, - |Unknown)| 2 | 42, 44 d | 26, 42 to 49 Spent ovaries, devel-
oping. Developing
ova ‘37 to ‘85mm.
November, |Unknown 2| 42, 44 Yellow developing
| ovaries.
December, |Unknown, 4 | 41 to43) 1) 42 Yellow developing
| ovaries. Ova, °*7mm.
* The ripe fishes are supposed to have been got to the south of Aberdeen.
+Sex not known.
§$The data given in this column do not include the condition in ev ery
one of the fishes.
+ Also a fish 47em.
, recently spent ;
sex unnoted.
In this species, as Kréyer* showed, the larvee develop in the ovary ;
internal fertilization is therefore necessary.
The adult fish is known by its having ripening reproductive
organs, or by its being spent.
Males measuring from 35 to 4.7 em. in
length were adult. Females measuring from 17-4 to 24, 26°65, 31 to
50, 74 cm., were adult. It is often easy to recognise a spent ovary
from the fact that larve may have been retained in it, and these,
although they have become shrivelled, betray their presence by the
black pigment of the eyes. A second character which is also of value
in the ovary is the presence of the old follicles, which can be recog-
nised for some time after the ovary is spent.
The adult fishes may be sexually distinguished, previous to
dissection, by the fact that in the male there is a large urogenital
papilla (penis), (pa., Fig. 62), while in the female this papilla is flattened
out into an apron-like tringe (ur. fr., Fig. 73). The urethra opens on
the apex of the papilla, and on the distal border of the fringe (with.,
*Collett, R,—“ Norwegian North Atlantic Expedition, 1876-1878,” Vol. ITI.
Zoology : Fishes. Christiana, 1880.
24 Fishery Board for Scotland.
Figs. 66 and 85). Sometimes a slender urinary papilla is present in the
female, e.g., in an immature fish 24 cm. long. In another fish the
papilla was flattened and had a fringe along two sides (Fig. 75). The
fringe in a female which had developing embryos in the ovary was
large (wr. fr., Fig. 73). In May the fringe was observed to be red,
suffused with blood. In the case of one pregnant female (May), a
red tube (?) projected from the oviduct. The filament which is
shown projecting from the oviduct in Fig. 85 may have been acci-
dentally torn from the wall of the oviduct. An enlarged drawing of
a fringe is shown in Fic. 66. Its ventral surface was deeply ridged,
especially so in the proximal half (fo.). It was less prominently ridged
at vi. It ended distally in translucent processes between which the
urethra opens. The upper surface of the fringe is practically plain.
This organ probably acts as an aerating organ in connection with the
developing embryos in the ovary.
A very marked difference exists between the two sexes in the size
of the urinary bladder. This is seen in Figs. 62 and 63, which repre-
sent the abdomen of the male and female fishes in natural size. The
urinary bladder of the male is enormous, (wrbl, Fig. 62). The urinary
bladder is a two-layered sac; the layers can be easily torn apart.
The external coat of the bladder is usually grey or black, on part of
its surface at least. The inside wall is deeply honeycombed and well
supplied with blood-vessels. The bladder usually contains a cream-
coloured or yellow fluid, in great quantity in the male, in small
quantity inthe female. The fluid, which is probably secreted by the
bladder, is albuminous ; it coagulates on the addition of water. Under
the microscope it is seen to contain corpuscles and oil drops of various
sizes. In the male the fluid issues by the apex of the papilla (wrth.),
while the sperm finds issue by a pore on the antevior side of the apex
(v.d., Figs. 89 and 90). The vas deferens is a wider channel than the
urethra. The fluid is probably injected into the ovary along with the
sperm, when impregnation takes place.
Development of the Testis.
In December, January, and February ripening testes are found.
The urinary bladder is very large. In January and February ripe milt,
which appeared to contain spermatophores, or groups of sperms, was
observed. One male had in its urinary bladder during February a
fluid that more nearly resembled water than the usual thick yellow
fluid. ‘Two of the testes werein this month apparently spent.
In March, April, May, and June the testes were all small. The
urinary bladder varied in size, but usually contained yellow fluid. In
two cases a collapsed bladder was found. Some of the small testes
were no doubt spent. In July and August the small testes showed
signs of beginning to ripen.
The testis was in September and October usually large and white
in colour. The urinary bladder was large. Impregnation probably
takes place in January and February.
Development of the Ovary.
The ovaries are separate (Fig. 85); the oviducts unite (j). The
ovary is pigmented black, or a dark grey, externally. The pigmenta-
Reproductive Organs of Sparus Centrodontus. 25
tion, which is more intense in the anterior half of the ovary, is mainly
on the dorsal, outer, and ventral sides. The side of the ovary which
is applied to the other ovary has little pigment. A row of small dots
was observed along the course of the principal blood vessel. In some
large ovaries which had been preserved, no black pigment was made
out.
The ovary consists of a sac which encloses the lobed mass of ovarian
tissue. The latter is attached to the wall along a narrow strip
merely (Fig. 72). The greater part of the wall does not bear ova. In
Lophius* one half of the ovarian walls bears no ova. In Fig. 84 the
wall (w.) of the ovary has been slit longitudinally to expose the ovarian
mass (ov.). The groove (ovd.) is the opening of the oviduct of the
other ovary. The wall which is opposite to the other ovary is
supplied with large anastomosing blood-vessels (Fig. 85). The vessel
v. is attached to the mesentery. A vessel runs down the oviduct; it
may go to the urmary fringe.
The immature ovary is colourless. A fish measuring 32 cm. in
length had in May a very small immature ovary. Great rolls of fat
were present in the abdomen.
When the ovary is ripening it is yellow. The colour is due to the
presence in the ova of yellow oil globules. In September a developing
yolked ovum, preserved, measured °37 x ‘3 mm.; it had a large
number of oil globules irregularly grouped (Fig. 74). The little eggs
projected like bosses. Fulton* describes the eggs of Lophius
piscatorius as projecting on stalks. The follicle is, like the stroma,
composed of little cells (sf.). The follicle appeared to be two-layered,
an outer smooth and an inner bossed layer. Some of the ovaries had,
during this month, eggs measuring ‘85 mm. in diameter, e.y., e, Fig.
88. The old follicles, which denote a previous spawning, are shown
(7l.). Another view of a portion of a ripening ovary is seen in Fig.
94. The larger eggs are now stalked.
In October very similar conditions are met with. ‘Two ripening
egos, the largest of which measured ‘5 mm. in diameter, are shown in
Fig. 93. The processes (pr.) observed among the eggs are doubtless
shrunken follicles. The eggs are developing along the side of a
vessel that has thick walls. The eggs seem to le inside the wall (e,
Figs. 91 and 92); the inner layer (vas.) appears to be vascular.
Ripening eggs in January measured from ‘4 to 1:0 mm. in
diameter. The eggs were opaque yellow, and were still in the
follicles, which are well supplied with blood vessels. The eggs, 1:0
mm. in diameter, broke away easily from the stalks. An opaque egg
1:0 mm. was filled with a yolk consisting of distinct corpuscles
which separated readily when the egg was torn open. ‘The
corpuscles, which were round and oval, measured about ‘05 mm.
in greatest extent. The immature egg (‘2 mm. in diameter) is filled
with minute oil globules, that give it an appearance recalling the egg
of the eel.
In February and March the eggs measuring from ‘8 to 1:2 mm.,
still in follicle, showed a central mass of oil globules, and a clear rind
outside it. The latter in some instances appears to consist of round
yolk corpuscles. Each egg had at least one big vessel attached to it.
*Fulton—‘‘The Ovaries and Ovarian Eggs of Lophius piscatorius and of
Zeus faber.” 2 pl. 16th Ann. Report of the Fishery Board for Scotland, for 1897,
Part III. 1898. P. 125, et seq.
26 Fishery Board for Scotland.
When the preserved follicle was cut open, the egg was found to have a
coarsely granular yellow core surrounded by a finely granular thick
rind. A female had ripe eggs free in the ovary, but no segmentation
of the ovum was made out. The stalks of the eggs are noteworthy :
some are very long (w., Fig. 83), others are short. The stroma exhibits
a network of fine fibres, and of vessels large and small. One fish had
a small ovary which was shrunken and mottled with brown.
April.—A fish had ripe eggs still in follicle. They measured 1:0
to 1:15 mm. in diameter and had a yellow oil globule measuring ‘37
and ‘4mm, in diameter. The eges were translucent. When free
from the follicle they appear to imbibe fluid quickly and swell up.
Developing embryos were found in the ovaries during April, May,
and June. The eges had become free from the follicle, and they filled
the ovary with a semi-fluid mass. The ege has a delicate investment ;
one coat only was made out. The embryos were found in various
stages from the “disc” stage up to the embryo which was ready to
hatch (Figs. 64, 65, 70,71). Larvee and post-larve were also found in
the ovaries (Figs. 69, 77, 78). The posterior end of the ovary was well
supplied with blood. Its wall was distended, and very thin, permit-
ting the ova and larvee to be seen from the outside.
The eggs varied in shape: some were oval, others round. Some
oval eggs measured in the fresh condition, 1:4 x 1:1 (oil globule -4) ;
1-4 x 11 (0.g. 4); 13 .x 1:05 (o.g. -4) mm. A round egg con-
taining an embryo was 1:12 (0.g. -4) mm. in diameter. Preserved
ovaries had eggs containing embryos measuring as_ follows :-—
15 x 112; 13;1:15; 105 mm. Among the small pregnant fishes
obtained in June two of the developing free ova measured while fresh
17 x 1:4 (0.g. 4), and 1:7 x 115 mm. The oil globule was green.
After preservation some ova obtained from the same lot of fishes
measured 1:7 x 1:35 (0g. 4); 155 x 13 (og. 4); 145 x 132
(o.g. 4); 14 x 1:35 (0.9. 42); 14 (0g 4); 1:4 x 18 (0.g. 4) mm.
When the egos have escaped from the follicles, the latter become
very large (7l., Figs. 80 and 86). They are well supplied with blood: a
elomerulus can sometimes be made out in the swollen end, The
ovarian lobes, ovl., thickly covered with these follicles, stick out
through the semi-fluid mass of ova (Fig. 59) The follicles are no
doubt concerned in the aeration of the embryos and larvee. In Fig. 80
two ripe eggs (e) are still in follicle. The young eggs are concen-
trated in groups on the large vessels of the ovarian tissue.
A fresh ege containing an embryo was put into formaline and it
rapidly became opaque white. It was soon difficult to make out the
oil globule and embryo. This was due to the fact that the
perivitelline fluid coagulated.
In preserved ovaries two kinds of eggs (with embryos) were found;
one an opaque egg, and the other a small translucent egg. When
some of the opaque eggs, which were usually large, although some
were small, were dissected, a thick outer finely granular opaque rind
was found inside the zona. When the rind was removed the embryo
was seen in several of the eggs, although not in all. When it was
found it was semi-circular in shape, approximately at the stage
represented in Fig. 65. In one large egg the embryo was visible
from the outside. The small translucent egg may also show the
embryo half-way round the yolk. Sometimes the zona is clearly
crumpled, as if the small ovum had lost the contents of its perivitelline
Reproductive Organs of Sparus Centrodontus. 27
space. Some of the small yellow opaque eggs exhibit the white
embryo on the outside.
Many of the eggs, then, found free in the ovary are larger than when
they are in follicile. They have imbibed some fluid. In the ovary
along with the free eggs there is a coagulable fluid, in which green
oil globules are floating. This is, I consider, the fluid which is secreted
in the urinary bladder of the male fish, and which is introduced into the
ovary along with the sperm. ‘The eggs when they escape from the
follicile imbibe this fluid, and in this way a perivitelline space becomes
formed. ‘The remains of the fluid present among the eggs is found in
the preserved ovary in the form of a granular solid, which is in the
form of strings filling the interstices between the eggs, or is attached
to the wall of the ovary in a honeycomb form (Figs. 57 and 58). — It
can be easily removed from the wall, but it has often attached to it a
delicate skin which has probably been torn off the ovary or its wall.
The material is translucent, and it encloses vesicles of various sizes ;
the latter resemble oil globules. In a preserved urinary bladder of a
male fish the yellow fluid was coagulated to a granular powder.
The early embryos show no pigment. In one in which the tail
nearly reached the head, no pigment was made out. The eyes were
visible ; the head was thick dorso-ventrally (Fig. 67).
When ready to hatch the embryos show pigment. In one (Iig. 71)
the eyes contained black pigment, but no other pigment was observed.
The yellow oil glubule was present and was still large. In others,
however, a row of black spots was visible along the ventral edge of
the post-anal body, but not extending as far as the end of the tail.
The black eyes of the embryos shining through the wall of the
yellow ovary cause the latter to appear greenish.
The embryos in an ovary appeared to be all of about the same
stage of development.
After the larvee escape from the egg they remain in the ovary
until the yolk is absorbed. Fig. 68 represents a larva which was
found hatched in an ovary containing embryos still in the egg. The
peculiar condition of the anterior end of the little fish is seemingly
due to the fact that that region is still enveloped in the zona. In its
bent condition the larva extended 3°25 mm.
A ventral view of the anterior end of a larva is shown in Fig. 69.
The mouth is a small pore situated between the eyes. The eyes
approach one another closely on the ventral surface. The round
pectoral fin (p7f.) is small. There are no jaws. In another specimen
a semi-circle could be traced across the mouth region. This may
indicate the line of separation between the jaws. A larva is
exhibited in side view in Fig. 77. It had been preserved. The eyes
were deeply pigmented. It had a characteristic blunt head. The
marginal fin was composed of little round cells. The tail fin had a
somewhat ragged edge. Pieces of cuticle were lying loose at si.
Some larvee measured from 3°7 to 4°3 mm. in length. The example
3°7 mm. long was bent. A little black pigment was present over the
eyes and on the region of the rectum. A row of pigment spots was
present on the dorsal and ventral edges of the hind half of the body.
The ventral row commenced a short distance behind the anus and
extended back to the beginning of the tail fin. Sometimes the
pigment on the post-anal body is not made out. A couple of the
largest larvee had the jaws formed.
28 Fishery Bourd for Scotland.
A few post-larvee were found in an ovary in June. One which was
drawn in the fresh condition is shown in Fig. 78. It measured
7 mm. in length. No yolk remained. The upper jaw was short, the
lower jaw long. The eyes were large, black, and silvery. [Fin-rays
were present in the caudal and pectoral fins. The pigment, which
was black, with perhaps some brown, was present on the top of the
head, over the rectum, and along the dorsal and ventral edges of the
long post-anal body. ‘The latter pigment reaches to the beginning of
the tail fin. The row on the ventral edge extends further forward
and a little further posteriorly than the dorsal.
A preserved post-larva, which was one of eleven found in an ovary,
is seen in Fig. 76. It measured 6:25 mm. in length. The marginal
fin is drawn as it was, but it should no doubt be similar to that fin in
Fig. 78. The pigmentation is similiar. In another larva, however,
there were nine spots on the head. Two other post- larvee measured
5-4 and 65 mm. in length ; neither was quite straight.
This is the condition to which the larva is reared hefore it is liberated
from the ovary.
According to Collett* ‘the length of Sebastes marinus at birth is
about 6 mm.; they are, however, immediately able to swim and
provide for themselves. On the Norwegian coasts the spawning
season generally extends from the middle of April to the middle of
May. Sebastes viviparus, on the contrary, does not as a rule produce
its young earlier than July or August. Examples of Sebastes marinus,
with fully-developed ova, are, however, occasionally met with late im
summer.” The same author’states that the fry appears to rise towards
the surface shortly, or perhaps immediately, after they are produced.
On June 9, 1910, a large number of small Sebastes, 17°7-24°4 cm.
in total length, was obtained. Fifty-four were examined, and they
were found, with two exceptions, to be pregnant females. This would
indicate a tendency of the pregnant females to shoal together.
M‘Intosh and Masterman? describe the larvee found in the ovary of
a specimen obtained in the Moray Firth. Comparing the old follicles
in this form with the similar organs in the ovary of Zoarces viviparus,
they suggest that the follicles supply amongst other things a nutritive
pabulum for the larvee.
Stuhlmannt has given a description of the histology of the ovary of
Zoarces.
Wallaceg§ has more recently described the early development of the
ovary, and also the histology of the villi of the pregnant ovary. He
also discusses the egg-membranes, and the mode of absorption of ova
that have been retained in the follicle.
Spent Ovaries.
A portion of a spent ovary in April is shown in Fig. 87. The old
follicles (j.) are dull granular in appearance ; they project from among
the young eggs. The egesare clear. The nucleus has not been shown
+ ‘* British Marine Food-Fishes.” London, 1897.
* Op. cit.
‘‘Zur Kenntnis des Ovariums des Aalmutter (Zoarces viviparus, Cuy.).” 4
taf. Abh. aus d. Gebiete des Naturwissenchaften. Bd. x., Hamburg, 1887.
§ ‘Observations on Ovarian Ova and Follicles in certain Teleostean and
Elosmobranch Fishes.” Quart. Jour. Micro. Science, Vol. 47, Pt. 2, N.S., p. 160,
3 plates.
Reproductive Organs of Sparus Centrodontus. 29
in each egg because, owing to the thick tissue, it was not always
visible. The eggs were beginning to store up yolk; they were
yellowish, and showed some oil globules.
In spent ovaries in May one or two larve similar to Fig. 78 were
found. The follicles were shrivelled up, but were still large. The
eggs were becoming yolked. The largest noticed measured *22 mm.
in one case and ‘25 mm. in another in diameter. No rolls of fat were
visible in the abdomen of the latter at least.
In June the ovarian tissue was in one spent reduced to the appear-
ance of a thick rod. The wall of the ovary was a slack skin. The
follicles were still big, and projected beyond the eggs, which were
becoming yolked.
In July spents were recognised by the few larvee left in the ovary,
and also by the presence of old follicles. The eggs in a small ovary
were becoming yolked; they stood out as round bosses. Smaller
clear eggs were visible among the yolked eggs.
In September the old follicles are still to be traced in the ovary
(Fig. 88).
Sebastes dactylopterus (Delaroche.) .
This fish was described by Delaroche under the name of Scorpoena
dactyloptera. Cuvier and Valenciennes, however, introduced it into
their genus Sebastes, because, in their opinion, it pertained more to
Perca than to Scorpeena. A number of authors, e.g., Nilsson,* Roule.t
Jaquet,¢ have made use of the name Sebastes dactylopterus (Delaroche).
Recently Holt and Byrne§ gave a detailed description, with figure, of
this form. ‘They conserve the original name of Scorpoena dactyloptera.
While admitting that this fish rather closely resembles Sebastes
marinus, they do not agree with its exclusion from the Scorpzenas.
The example described by Delaroche was obtained in the Mediter-
ranean.
The fish is red-coloured. There is usually a black patch visible on
the outside of the operculum. It is caused by the black inside
surface of the operculum shining through the bone. This colouration
is not, however, always evident.
There is some brown colour on the dorsum; sometimes there are
greenish patches also. Two large specimens, about 40 cm. long, showed
a good deal of brown pigment in this region. In one fish 33 cm. long,
the brown was absent, or only traceable on close examination. One
female had only pink colouration on the top-sides. There were
white blotches scattered over the skin; they were prominent in most of
the specimens, and could be traced in all.
When the fish lies damp for two or three days the red colour changes
to amber. Fishes which had been preserved some time in formaline
showed a thick spreckling with brown pigment on the dorsum, and on
the sides above the lateral line chiefly.
* Vide Roule.
+t Roule, L.—‘‘ Notes Ichthyologiques—Les Scorpénidés de la Mediterranée.”
Arch, de Zool. Expérim. et Générale. 1907 [4], Vol. vi. Notes et Revue, No. 1,
p- Xiv.-xxiv.
{ Jaquet—‘‘ Considérations sur les Scorpénides Mer de Nice.” Bull. de
V Institut Ocednographique. No. 109, Dec. 1907. Monaco.
§ Holt and Byrne—‘‘ Second Report on the Fishes of the Irish Atlantic
Slope.” Fisheries Ireland Sci. Invest., 1906, V. [1908].
30 Fishery Board for Scotland.
Bars may be sometimes traced on the sides, but often they are not
at all clear. Three were noted in one fish. ‘The first came down posterior
to the operculum; the third was located below the soft part of the
dorsal fin, while the second bar was located about mid-way between the
two former. Several black or amber blotches were observed on the
dorsal fin. The front part of the inside of the mouth is white; the
pharynx is black or blue. The under edge of the gill-cover and
branchiostegal apparatus was whitish.
The peritoneum is jet black.
Stellate black pigment corpuscles were observed on the wall of the
stomach of one fish.
The uriary bladder is very small.
The swim-bladder, as Delaroche* pointed out, is absent,
Fig. 106 represents a specimen of this species. The correct number
of fin-rays is not shown in every case. The scales are diagrammatically
represented.
The eyes are very large. The orbit is oval.
The jaws are nearly equal when the mouth is closed; the
mandible does, however, project a little in front of the premaxille.
The horizontal membrane is present inside the lip of each jaw; it is
narrow. ‘Teeth are present on the vomer and palatines, in addition to
the premaxille and dentaries. ‘The teeth are all small.
The short ridge over the eye is often toothed, as many as six or
seven teeth being made out. Sometimes it does not show teeth dis-
tinctly, but is simply a rough ridge. This condition may occur on one
side of the fish, while three well-defined teeth may be present on the
other side.
The head in side view is gently rounded.
The top of the head is depressed. The interorbital space is bounded
on either side by the prominent ridge which forms the upper edge of
the orbit. It is longitudinally hollowed out and bears, projecting from
its sloping sides, two prominent ridges shown in rd., Fig. 103. The
interorbital space in Sebastes is flat, and the two secondary longitudinal
ridges are absent.
The scales are ctenoid (Fig. 99). No scales were present on the out-
side of the lower jaw.
The number of pyloric ceeca was in two cases seven, and in one
Case 81x.
Dorsal Fin.—The dorsal fin consists of two parts—a longer portion
composed of spines, a shorter portion consisting of soft rays. In ten
fishes only a shght variation was found in the number of fin-rays. In
each of eight fishes the rays numbered 12 spines and 13 soft rays,
while in two specimens the numbers were 12 spines and 14 soft rays.
The 12th spine is longer than the spine preceding it. In one fish
the longest spines were the 3rd to 6th.
The first two spines and the last two rays arise from a single inter-
spinous bone in each case. The last two rays are close together at
their bases. The angle between the last ray and the dorsal edge of
the body is filled with a little membrane.
Anal Fin.—The anal fin consists of three spines and six soft rays.
These numbers were found in all the fishes in which the character was
noted, viz., eight. The first two spines and the last two rays arise
* Vide Cuvier et Valenciennes, op. cit.
Reproductive Organs of Sparus Centrodontus. 51
from a single interspinous bone respectively. The last two rays are
close together at their hases. Sometimes all the spines of this fin are
covered with thick skin. The angle between the last ray and the
ventral edge of the body is filled with a little membrane ; it is usually
not so large as the membrane at the end of the dorsal fin.
Pectoral Fin.—The pectoral fin furnishes an important specific
character. Its lower ravs are thick and fleshy, and separated from
one another in a considerable proportion of their length. The upper
part of the fin contains thin rays which have each from one to four
points. This part of the fin is cut square across. The total number
of rays was 19 (11 thin and 8 fleshy) in seven fishes, and 20 (11 thin
and 9 fleshy) in three fishes. Of the thin rays the first and second
had single tips; the third to tenth were split into more than two
tips; the eleventh ray was either single or split into two at the tip.
The fleshy rays are single. The fleshy rays are separated from each
other in from one-third to one-half their length. They were
often damaged. Sometimes certain of the rays were fixed bent at a
sharp angle, as if they had been broken across and had healed in the
bent condition. They may be damaged on one side of the fish and
normal on the other side. In one fish several of the fleshy rays had
been cut off on both sides.
The longest ray in the fin is sometimes one of the last thin rays,
but in other cases it may be one of the first fleshy rays, e.q., the 14th ray.
The axilla of the pectoral fin is deep, and there is much slack skin in it.
Ventral Fin.—Vhe number of rays in this fin was counted in six
fishes. No variation was found, the number being one spine-ray and
five soft rays. There is a broad membrane binding the last ray to the
ventral surface of the body (imb., Fig. 100). The spine-ray is entirely
covered with thick skin.
Caudal Fin.—Twenty-four rays were counted in the case of one
fish. The dorsal and ventral edges of the base of the tail form some-
what sharp ridges. The top and bottom edges of the fin are often a
little irregular, as if the rays had been shorn. The lowest three or
four rays are sometimes of a thicker form than the other 1 rays. The
hind margin of the fin is either straight across or slightly concave.
Veriebre.—In 12 fishes the number of vertebrae was not found to
vary. ‘l'wenty-five were found in each case. The first hemal arch
was in twelve cases on the seventh vertebra; the first heemal spine
was in three cases on the eighth; the tip of the hemal spine
was forked in one case. The end of the first interspinous line of the
anal fin met the heemal spine of the eleventh vertebra in two instances.
Measurement Characters
Certain measurements similar to those made on Sebastes marinus
were recorded for this species. The results have been introduced into
the ‘Table on page 18.
Comparison between Sebastes dactylopterus and Sebastes marinus.
In colour they are very similar, both being red-coloured. The red
colouration differs in the two fishes in its shade.
In side view the two species closely resemble one another.
Important differences are also detected. Generally Dactylopterus is
52 Fishery Board for Scotland,
not so deep a fish as Marinus. The hump on the dorsal edge, in front
of the fin, is a prominent character in Marinus, while it is absent in
Dactylopter us. The orbit of the former is round; that of the latter is
oval. The orbit of Marinus is the larger.
The pectoral fin forms an important distinguishing feature. The
upper part is cut square across in Dactylopterus, while in Marinus the
distal border is oval. ‘The lower rays in the former fish are thick and
much separated from one another; in the other species the lower rays,
although they are thicker than the upper rays, are not so fleshy as
those of Dactylopterus, and only their tips are free.
The lower jaw in Dactylopterus is not so prominent as in Marinus;
the maxilla, although large in both species, is the bigger in the
former.
The lateral line differs slightly in the two species. In Marinus it
forms a more extended curve in its anterior half; im Dactylopterus it
begins to descend immediately behind the operculum.
When the head is viewed from above an approach to the broad head
of Cottus and Scorpeena is seen in Dactylopterus (¢.g., Fig. 114); im
Marinus the head is narrower (Fig. 115). The interorbital region of
the former is hollowed out, while it is flattened in the latter. —
Well-marked differences occur in the numbers of the fin-rays (vide
pp. 19 and 30). The membrane between the last ray of the dorsal and
anal fins and the edge of the body is more extensive in Dactylopterus
than in marinus. The colour of the inside of the mouth forms an
important distinguishing feature. In Marinus it is white or pink; in
Dactylopterus the pharynx is black or blue. The two species exhibit
intermediate conditions between the forms Perca and Scorpeena. At
one end of the series Perca is closely resembled by Sebastes marinus,
while Sebastes ductylopterus shows in its general form and external
features a near approach to Sebastes on one hand, and on the other
indicates, in respect to its head, a tendency towards the form of
Scorpeena (e.g., Porcus). The classification of these fishes is not satis-
factory. But any alteration demands a study of all the allied
fishes.
The Reproductive Organs.
The male has a large muscular external urogenital papilla (pa., Figs.
106 and 112). There are upon it two crater-like orifices, the anterior
of which is the opening of the vas deferens, while the posterior one is
the aperture of the urethra.
In the female there is sometimes a small urinary papilla (wr. pap.,
Fig. 111). The external aperture of the oviduct is wide (ovd.). It
lies between the anus and the urinary papilla. The hind edge of the
anus is expanded into a crescent-shaped lip which lies over the vulva
(fr., Fig. 110). The flap varies in shape and size (Fig. 110, A and B).
The hind lip of the vulva is sometimes prominent also. The urethra
opens to the exterior a little below the apex of the papilla, and on its
anterior side.
The Urinary Bladder.—Ma.teE—The urinary bladder was small and
jet black on the outside. It was sometimes empty; but in one or
two cases it contained a clear fluid like water. In les on the right
side of the black mesentery that supports the vas deferens and the
ureter to the roof of the abdominal cavity. The ureter is median.
Reproductive Organs of Sparus Centrodontus. 33
FremMaLE—The urinary bladder resembled that of the male.
It is on the right side of the mesentery. In four females the bladder
contained white granular fluid. The inside of the bladder was longi-
tudinally ridged.
Testis.
In fishes measuring from 42 to 45 cm. in length in January the
testis was large and white. A drawing of the testis in natural size is
given in Fig. 112. The vas deferens is a thick-walled tube, apparently
muscular.
In two fishes measuring 37 and 43 cm. in length the testis,
although white, was small.
In February some of the testes were ripe in fishes measuring from
40 to 46 cm. in length. They contained milt of a white pasty nature.
The vas deferens was distended with milt.
One fish in March measured 45 cm. in length. It had a white
testis.
The Ovary.-—January, February, March.
A general view of the ovary and its connections is given in natural
size in Fig. 111. The ovary is remarkable: it is a long, narrow,
flaccid organ. Its anterior end is bent on itself. It exhibits on its
external surface a good deal of black pigment. If the outer wall be
slit open (Fig. 108) the true ovary (lov.) is found lying loose within,
except for the attachment to the skin formed by the blood vessel (bv.)
at the anterior end. The ovary was dark red: it was well supplied
with blood vessels. The line along which the mesentery is attached
on the outer surface is indicated by the groove (qro., Fig. 108). In the
preserved condition the ovary was flattened: it was of one breadth in
its whole length. The internal surface of the sac is ridged with
longitudinal muscles. In some of the ovaries the outer wall was
slack.
The united oviduct is opened to show the junction of the right and
left oviducts (7. ovd, 1. ovd, Fig. 111).
If the ovary be cut across, it is found to consist of a thick rind which
encloses a space occupied by a loose network tissue (Fig. 107). In
this central space two large blood vessels, an artery (a7) and a vein (bv)
are to be seen. They break up into a network of vessels that fills up
most but not all the space. Yellow gland-like bodies are present at
gl.
The rind consists of a basement layer supporting columns or septa
filled with eggs. Each column has two layers of eggs, between which
is the principal blood vessel. At the ends of the columns a few eggs
project on little stalks; they are becoming yolked.
An enlarged drawing of a portion of a column is shown in Fig, 102.
The basement layer consists of round nucleated cells, accompanied by
branching vessels, some of which have rigid walls, and therefore stand
open. Some of the vessels had ceecum-like branches. Hach ovum is
contained in its own skin, and is supplied with blood vessels that go
between the eges. Some of the fibres on the inside of the column were
wavy: they are probably muscular. Fig. 101 shows a theoretical
section of a column. The column appears to be a sac enclosing two
54 Fishery Board for Scotland.
layers of eggs; it probably is the follicle of the ovum. In the centre
are the blood vessels (bv.), and on either side are the ova. A loop (bv’)
from the blood ene is shown encircling each egg.
There appear to be differences among the blood vessels. The main
blood vessels have walls composed of fibres, while the small blood
vessels in the ovarian tissue have a wall of two layers at least, a fibrous
layer and a cellular layer. The cellular wall consists of small round
nucleated cells.
The skin that covers an unyolked egg (imm.) is thin; that which
covers a yolked egg is thick (yk., Fig. 102). In the follicle of the
latter there is between the outer skin and the zona of the egg a thick
layer of round cells (pl., Fig. 104). This layer extends into the stalk
of the egg. This placental layer is evidently attached to the vascular
layer (vas.), but is independent of the follicle (#.). It apparently comes
away with the egg when the follicle is ruptured. The cells composing
the layer are similar to the round nucleated cells of the basement
layer. Such cells may be seen along the vessels and concentrated in
gland-like bodies. The follicle, although cellular, is more dotted and
not distinctly cellular on the stalk portion.
The modus seems to be as follows. The egg which is about to
ripen has a layer of round cells developed round it. | How they arise
is not clear. Whether they are developed in situ or transferred there
is an open question. This cellular layer, which is a sort of placenta,
apparently secretes the yolk which the egg absorbs. The yolk con-
sists of small corpuscles.
The egg-columns are thickly arranged over the surface of the ovary.
They are not all of the same height. The yolked eggs are often
terminal; some, however, come off the side, and even well down at the
base of the column.
In January the ovaries in fishes 39 and 41 cm. long had not
developed far towards ripeness. A few white yolked eggs measured
‘27 mm. in diameter. The nucleus was visible. The clear eggs
measuring ‘25 mm. in diameter had some white pigment round the
edge of the nucleus.
In February fishes measuring 28°5 and 35 to 41 cm. in length
were examined. In the fish 28:5 cm. long a small (though long)
immature ovary was found.
The ovaries in the others was very similar to those examined in
January. The naked-eye appearance of the ovary was almost
colourless, with only a pale pink colouration. Most of the eggs were
clear. Some were beginning to store up yolk, The yolked eggs
measured up to °27 mm. in diameter. Here and there in the ovarian
tissue there were patches of white granular matter (gr., Fig. 109). It
appears to be a coagulated albuminous matter. It was observed in
more than one ovary, and in one case it was in greatest quantity in
the oviduct. In parts it had assumed a cellular form.
In March a female 40 cm. long was obtained. The largest yolked
egos were ‘35 mm. in diameter. An enlarged portion of the ovary,
which had been cleared with a solution of sodium-hydrate, is shown
in Hig. 105. Some of the terminal eggs have long stalks. The
small eggs appear to be more numerous than in the ovaries examined
previously.
Some of the white granular matter was seen in the ovary (g7., Fig.
105). The general structure of the ovary in this fish would suggest
Reproductive Organs of Sparus Centrodontus.
the likelihood of the mode of development being viviparous. In none
of the ovaries, however, were any old follicles, egg-capsules, or larvee
observed. Holt* says that this species appears to be oviparous.
A live nematode was found inside one ovary.
*** Recherches sur la Reproduction des Poissons Osseux.”’
d Histoire Naturelle de Marseille.
a, an.—Anus, anal.
ab.—Abdomnien.
ar.—-Artery.
bv.—Blood- vessel.
e.—Concretion, cyst.
cv.—External ciliated edge of scale.
cl.—Clear process.
col.—Column.
d.—First portion of gut.
df.—Dorsal fin.
dm.—Dorsal mesentery.
e.—Egg.
f.—Fat.
fl.—Follicle.
fo.—F oliated surface.
jfr.—Fringe.
g.-—Gut.
gl.—Gland.
gr.—Granular matter.
gro.—Groove.
he.—Heemal canal.
hd.—Head.
imm.—Unyolked eggs.
int.—Interspinous bone.
j.—Junction of oviducts.
k.—Kidney.
—Wett.
la.—Lacunar tissue.
lar.—Larva.
l. ov.—Left ovary.
l. ovd.—Left oviduct.
m.—Mesentery.
mb.—Membrane.
mo.—Mouth.
neu.—Neural canal.
oc.—Eye.
og.—Oil globule.
LETTERS USED.
ot.—Otocyst.
ov.—Ovary.
ovd.—Oviducet.
ovl.—Ovarian lobe.
po.— Urogenital papilla.
pap.—Papilla.
per.—Peritoneum.
pf.—Pectoral fin.
pi.—Pigment.
pl.—Placental layer.
v.—Right.
rd.—Ridge.
rect.—Rectum.
ri.—Ridged surface.
r. ov.—Right ovary.
r. ovd.—Right oviduct.
sf.—Surface of follicle (Fig. 74).
sk.—Skin.
sm. e.—Small egg.
sp.—Spongy tissue.
spe.—Space.
sw.-bl.—Swim-bladder.
t.—Testis.
ul.—Upper lip.
uovd.—United oviduct.
ur.—Ureter.
urbl.—Urinary bladder.
urfr.—Urinary fringe.
urth.—Urethra.
v.—Vessel.
vas.— Vascular layer.
v. d.—Vas deferens.
vf.—Ventral fin.
vm.—Ventral mesentery.
w.—Wall.
yk.——Yolked.
Ann. du Musée
Zoologie. T. 5. Marseille, 1899.
ire? ae
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2
oot
on
oe &
.
—
So WIS
PLATE L
(Sparus centrodontus, Delaroche.)
Abnormal reproductive organ of fish 47 cm. long.
Side view of abdominal cavity of fish 44 cm. long.
Fish 42 cm. long, with secondary anus.
Reproductive organ. January. Nat. size.
Sparus centrodontus.
Pelagic egg (7 Sparus centrodontus). Enlarged.
Side view of abdominal cavity of fish 46cm. long.
Drawing of gut at secondary anus (Fig. 3). Enlarged.
Section across reproductive organ. January. Testis nearly ripe; ovary
immature.
Reproductive organ ; testis large, ovary small. January. Nat. size.
Portion of section of testis. Enlarged.
Cross section of a developing testis. Hnlarged.
Embryo dissected out of the pelagic ovum (cp. Figs. 5 and 13). Hnlarged.
Pelagic egg (? Sparus centrodontus). Enlarged.
External view of secondary anus (cp. Figs. 3, 7, 15).
Sketch to show the portion of the gut passmg through the abdominal
wall to the secondary anus.
Portion of ripe testis (Fig. 9) seen from outside. Knlarged.
Reproductive organ ; testis and ovary equal in size. Nat. size.
Section across the reproductive organ shown in Fig. 17.
Abnormal reproductive organ. January.
Drawing of opaque yolked eggs, in swollen follicle, in developing ovary
January.
Reproductive organ. January. Nat. size.
99 7}») Pe) 9
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: (1312€). 403/48. 500, 4/11, BANKS & CO. L*D.
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PLATE II.
(The figures refer to Sparus centrodontus, except where otherwise stated.)
RIG:
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FIGs.
Fic.
biel
S35
23.
24.
25.
26.
27.
28.
29.
30.
Sl.
32.
30.
51.
52.
53.
54.
56.
57
59.
60.
61.
Portion of oviduct-wall of ovary of a fish 46em. long. | November.
Enlarged.
Section of testis of fish 43cm. long. November. Enlarged.
99 99 99 99 9 >
99 I) bh) ” ” 9
Section across the oviduct of fish 43cm. long. November. Enlarged.
Section across the union of the oviducts.
The apertures in the cloacal slit of a predominating male 46cm. long.
Enlarged.
Sparus cantharus, Linn. 40°5 em. long. :
Longitudinal section through the cloacal slit of a predominating male.
Enlarged.
Section across the oviduct a little posterior to the position of Fig. 27.
Enlarged.
Section of oviduct of predominating male 36cm. long. November.
Enlarged.
Section of the same oviduct as Fig. 33, but close to the abdominal wall.
Enlarged.
Oviduct of the same fish as Fig. 24, opened at its external aperture.
View of internal surface. Enlarged.
Drawing showing dentition in lower jaw of Sparus cantharus. Approxi-
mately natural size.
Lower jaw, to show dentition. Approximately natural size.
Reproductive organ, about natural size.
Reproductive organ. January. Dorsal or posterior surface.
Spent ovary developing, of fish 44cm. long. November.
Horizontal section of urogenital papilla of a predominating female,
42‘5cm. November.
Section at A of reproductive organ shown in Fig. 38. Enlarged.
>
Lasoo ae? Ree So a ”
Diagram of developing egg: p7. indicates pigment in the nucleus. En-
larged.
Section at A of the reproductive organ shown in Fig. 40. Enlarged.
99 B 99 9 O') be)
C bie)
99 3 9 be)
Section of the reproductive organ of Sparus cantharus, about the middle
of its length. Enlarged.
Section of the reproductive organ of a fish 46cm. long across the
junction of the ovaries. Enlarged.
Section of the same reproductive organ as Fig. 49, but posterior to the
junction of the ovaries. Enlarged.
Diagrams of early developing eggs, showing different sizes of nuclei.
Views of concave surface of the otolith of Sparus cantharus. Nat. size.
Edge view of the otolith of Sparus cantharus.
View of convex surface of the otolith of Sparus cantharus.
Sebastes marinus, female, 37 cm. long. Reduced.
and 58. Sebastes marinus. Solidified albuminous matter from surface
of the wall of the ovary. Enlarged.
Sebastes marinus, section of pregnant ovary.
Scale of tish 38cm. long. About natural size.
Sebastes marinus, 40 em. long. Scale about natural size.
PLATE Il.
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(1312£) 403/46, 500, 4/11, BANKS & CO.LTD.
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63.
64
66.
67.
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Sebastes marinus, male, abdomen. Nat. size.
female “8 re .
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and 65. Sebastes marinus, developing eggs. April.
Sebastes marinus, female, urinary fringe. Enlarged.
93
9
9
side view of head of embryo. May. The tail of the
embryo nearly reached the head. Enlarged.
larva, just hatched, abnormal. Enlarged.
head of larva, recently hatched. Enlarged.
developing embryo. The preserved egg measured
125mm. April. Enlarged.
female, 34°5cm. Developing embryo. May. Enlarged.
section of ovary. September.
pregnant ovary. Nat. size.
developing yolked egg, °37 x 3mm. September. En-
larged. ;
female, spent. Urinary papilla. Enlarged.
post-larva, 6°25mm. long, from ovary. June. En-
larged.
larva, length 49cm. May. Enlarged.
post-larva, 7 mm. long, from ovary. June.
small egg, about ‘4mm. in diameter, becoming yolked.
January.
portion of ripe ovary. April. Enlarged.
*
PLATE til.
(y312€). 409/46. 500. 4/11. BANKS & CO. LTO.
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PLATEAY:.
Sebastes marinus, portion of a large ovary. February-March. Enlarged.
s5 ss
spent ovary. September. Ovarian wall slit open.
spent ovaries and external apertures.
portion of ovary. April. Showing very large follicle.
Enlarged.
spent ovary, developing. April. Enlarged.
- a September. Enlarged.
male, urogenital papilla. February.
section of urogenital papilla of male. February.
Enlarged.
young egg in wall of vessel in ovary. October. En-
larged.
developing egg in ovary. October. Enlarged.
pe) eggs 9 2
portion of spent ovary. September. Enlarged.
longitudinal section through the anal region of
female. Enlarged.
dorsal fin, last interspinous bone and last two fn
Enlarged. Semi-diagrammatic.
anal fin, last interspinous bone, and last two rays.
vertebra beari ing the first hzemal spine.
dorsal fin, end of, showing membrane joining the last
fin-ray to the dorsal edge of body. .
Sebastes dactylopterus, 41cm. long. Scale. Nat. size.
9 be)
view of adnate ventral fin.
theoretical section of egg-column of ovary.
portion of ovary. January. Enlarged.
view of top of head, showing the interorbital and
adjacent regions.
egg beginning to store yolk. Semi-diagrammatie.
Enlarged.
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106.
107.
108.
LO9.
110
AGW E
112.
113.
114.
115.
PLATE V.
Sebastes dactylopterus, portion of ovary, cleared with solution of NaOH.
March. Enlarged.
= me x1. The scales are not shown in correct size.
5 a transverse section of ovary. January. Enlarged.
. 5 ovary. January. Nat. size.
SS 35 transverse section of ovary, showing the granular
matter attached. February. Enlarged.
A and B. Sebastes dactylopterus, ventral views of the anal regions of
two fishes.
Sebustes dactylopterus, ovary. February. Nat. size.
= testis. January. Nat. size.
Sparus cantharus, end of dorsal fin, to show process formed by scales.
Sebastes dactylopter us, head seen from above.
Sebastes marinus, head seen from above.
PLATE V.
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a 3 | ‘4
FISHERY BOARD FOR SCOTLAND.
SCIENTIFIC INVESTIGATIONS,
iS TO;
No. IL.
THE RETARDATION OF THE DEVELOPMENT OF
THE OVA OF THE HERRING
(witH 1 Puate).
BY
H. C. WILLIAMSON, M.A., D.Sc., F.R.S.E.
This Paper may be referred to as:
“Fisheries, Scotland, Sci. Invest., 1910, Ul. (Sept. 1911).”
LONDON:
PUBLISHED BY HIS MAJESTY’S STATIONERY OFFICE.
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FISHERY BOARD FOR SCOTLAND.
REPORT ON THE RETARDATION OF THE DEVELOPMENT
OF THE OVA OF THE HERRING.
BY
H. CHAS. WILLIAMSON, M.A., D.Sc., F.R.S.E..
Marine Laporatory, ABERDEEN,
(Plate I.)
CONTENTS.
PAGE
The Methods Employed, : : : : : : 3
The Rate of Movement of the Apparatus, : : 4
Table of Temperatures, etc., ; : : ; : 5
Results.—The Uncooled Spawn on Gravel, : ; : : 6
The Spawn Incubated in a Galvanized Tin, 6
Cooled Spawn, . 7
Gravel and Glass, i : 2 : : . 8
Exposure to Light: Growth of Diatoms, d : : 8
The Current of Water, ; : : , : 9
The Filter- Barrel, : : : : : : 9
Experiments with Spawn from Live and Dead Herrings :—
On Galvanized Wire Gauze and Glass Plates, . 2 9
Milt and Spawn, . J : : ; : F 10
The Crystals in the Eggs, : : 3 : ; ; 10
Recommendations, : : : : ; : 11
The experiments on the retardation of the herring, which have been
carried on at the request of the Government of New Zealand, were
continued during the spring of 1911.
The eggs were fertilized on board a fishing boat on the evening of
27th February and the morning of the 29th February. The spawn
was obtained from live herrings caught in a drift net. It was
attached to glass plates and also to coarse gravel, as it was desired to
see how the two methods compared in respect to the well-being of
the ova. The method adopted in the case of the glass plates was
similar to that described in my previous paper.* For the second
method a layer of gravel was put on the bottom of a barrel partly
filled with sea-water. Some milt was pressed out into the water, and
then some spawn was pressed out and allowed to fall on to the gravel.
The gravel was left undisturbed for some hours. Twelve hours or
more later, the barrel, on arrival at Aberdeen, was tipped up and the
gravel turned out into a tub. A considerable quantity of the ova
* ** Experiments to show the Influence of Cold in retarding the Development
of the Eggs of the Herring (Clupea harengus, L.), Plaice (Pleuronectes
platessa, L.), and Haddock (Gadus eglefinus, L.).” Twenty-seventh Annual
Report of the Fishery Board for Scotland, Part II1., 1910, p- 100,
(4189.) Wt. 10769/231—500—9/1911,
4 Fishery Board for Scotland,
was not attached to the gravel. Some eggs had been killed. A fair
amount of ova was still adhering to the stones. They hatched out
well, as did some of the eggs which were found loose among the
gravel. The spawn was divided up. Part of both lots was cooled,
while the remainder was kept in uncooled water. The glass plates,
both cooled and uncooled, were made to revolve. The spawn on
gravel, both cooled and uncooled, was put into trays, which were
moved vertically. The revolution of the plates, and the raising and
depressing of the trays. was intermittent, not continuous. The trays
were made of wood, and they had bottoms sparred with glass tubes,
and in one case covered with old galvanized wire netting.
The uncooled glass plates were put into the apparatus used in the
1910 experiment. * It consisted of a galvanized iron box, which
revolved inside a galvanized iron tank.
The apparatus used for the cooled spawn was of wood, most of
which was tarred. The box containing the plates was 21 inches
square and 18 inches deep (A., fig. oy, A wooden frame, which
carried a plate on each of its four external faces, revolved on iron
axles. Each plate was in succession brought to meet the inflowing
current of water.
In the case of the uncooled gravel spawn the trays were raised a
little and then depressed. The cooled gravel spawn was arranged in
trays that travelled round on a revolving frame (B., fig. 2). The
trays were 9 inches by 7 inches by 2 inches deep.
The water was filtered through a barrel filled with sand, both for
cooled and uncooled ova.
For cooling the water a series of galvanized iron pipes (#-inch wide
diameter), covered with ice, was employed.
Sea-water had been running through the pipes and the apparatus
for three months before the ova were introduced.
The spawn was put into running water by about 10 p.m. on the
28th February.
The temperature of the uncooled and cooled water, and the
quantity of water supplied to several of the lots of eggs, are shown in
the table, p. 5. The temperature in °C. was read almost hourly
during the day and night. The maximum and minimum thermo-
meters were read once, sometimes twice, a day. The temperatures
given in the maximum and minimum columns refer to parts of two
days. The quantity of water is indicated by the time required to fill
a one-pint measure (‘6 litre).
An estimate was made of the number of eggs on two plates, which
were not too crowded with ova. They contained approximately 2600
and 2800 eggs respectively.
RATE OF MOVEMENT OF THE APPARATUS.
The cooled glass plates revolved once in from 1 to 2 minutes. The
cooled gravel in trays made a revolution in from 5 to 105 minutes.
The plates in the tin revolved once in from 14 to 2 minutes. The
uncooled gravel spawn in trays was raised and depressed once in 5$
to 74 minutes.
* ‘Experiment in retarding the Development of the Eggs of the Herring.”
Twenty-eighth Annual Report “of the Fishery Board for Scotland, Part IIT., 1911.
Lhe Retardation of the Development of the Ova of the Herring.
IncUBATION OF HERRING OvA —TEMPERATURE OF THE WATER, ETC.
Number of Days.
OMADIFWNHr
|
TEMPERATURE OF THE WATER.
capacity of 1 pint (=‘6 litre),
* The quantity of the flow of water is indicated by the tiie required to fill a vessel of a
(2) FLow oF WATER.*
i Glass @) Ur |
Gravel. Pinte Tin. cooled.
Range in | Max. and | Max. and Max. and | Max. and Nos. | Tin epee
nce Min. °F. Min, “Ey | Min. °F. | Min. ee: 1 and 2. Gravel.
- ee Secs. | Sees,
3—2°6) 42, 40 43,40 | 42°5, 40 40 ae se
d4—2°6) 42, 37 42,37 | 42°5, 41 ies - 4] | 22 95
3°2—2 38, 56 40,36 | 44:5, 43 | 44 5, 43 fe | ate
4—1°6} 38, 36 40,36 | 42°5 43'5 Be 22 a)
2°5—1°6| 38, 35 40,35 | 44°5, 39 | 44-5, 39 | ea
2°6—1°6, 36, 35 DD, ap) Pele: 4h 4g: 5, rel ere jt
2°2—1:4| 36, 35 37,36 | 41°5, 40 41°5, 40 9—2] : we
2°1—1°4)35+,35] 36,36 | 39°5 39°d 9—1 | 21,30) 14,18
1:9—1°4) 35+, 35] 56,35 | 42:5, 40 | 42°5, 40 18 22 Ly pS al
1°9—1°6| 37, 35 36, 35 | £2°5,°39 | 42°5, 39 | 16, 21 Dia) |) alts?
1°9--1:4) 35, 35 35, 35 | 42°5, 39. | 42°5, 39} 16, 22 27 20
1-9—1°4| 35, 34°5| 36,35 | 41°5, 39 | 41°5, 39 | 14—26|] 22 x
‘S+—1:4| 35,34 (35:5, 34:5] 40-5, 39 | 40°5, 39 |} 13—18| 238 38
2°2 —1-°3) 36, 34°5 | 36, 34°5 10—26| 30 5
2—1°'4| 36, 34:5] 36, 35 Be ae 14—23| 25 ae
2°4—1°6| 36,35 | 36, 35°5 | 40°5, 38 | 40°5, 38|}13—18| 44 | 46
22—1-7} 36,35 | 36, 35°5 ae ie 11—27 /18—46| 10
2— 1:6} 35°5, 35 | 36, 35°5 | 41°5, 40 | 41°5, 40 | 13,17 19 P10. 29
2—1°4/35°2, 34°5) 35°5, 35 : 10—15 5 | re
1°7 — 1°4/35-2, 34°5) 35°5, 35 iB 11—16); 19 31
19—1°3| 35,35 | 35:5, 35 | 40°5, 37 | 41-5, 39 18
2—1°6| 35°2, 35 | 35°5, 35 | 36, 35 ! 13—18 ~ ae
1°8—1°6/35°2, 34°5| 35°5, 35 | 37 41°5, 40 | 14—18] 100 32
2—1°4/35°2, 34°5) 35-5, 35 | 37,35 | 39-5, 39 17 35 30
2—1°4/35°2, 34°5| 35°2, 35 | 37, 35°2 | 42 eee) 34 32
1°8—1°4/35°5, 34°5) 36, 35 ihe ae ve 16 25
1:9—1-4/35°5, 34:5] 36, 35 dt,9) (42°3, 40) 16 40 j
2—1-4| 35, 34:5 | 35°5, 35 | 37,36 | 42:5, 41) 18, 20 Se |
1‘9—1-°6} 35,35 | 36, 35°5| 37,36 | 42°5,41/ 20 65 |
1:9—1°6] 35, 34:5 | 36, 35:5 | 37, 36 ; /15—231] 55 |
2 —1-6|35-2, 34-5] 36, 35-5 | 37-5, 36 PE eo 75 |
2—1:4|35°2, 34°5) 36, 35°5 | 37:5, 36 | 43:5, 41 |16—28) 65
2—1°4/35-2, 34°5) 35°5, 35 | 37,36 | 42-5, 41 |17—26
1°9—1:2| 35,34 (35:5, 34:5) 38,35 | 42°5, 40] 15, 28 $i
1°8—1-4| 30, 34:2 |(35°5, 34-5) 37,35 | 41°5,39/13—17| 63
1°8—1°2| 35, 34:2 |35°5, 34:5) 37,35 | 40°5,39|)14—17| 63
1‘8—1:2| 35,34 |35°5, 34:5) 36,35 | 39:5, 38|}14—30| 65
1°8—1°6} 35,35 | 36, 35:5 | 37°5, 35 | 42°5, 39 | 15—30
1:9 — 1-3)35:2, 34:2} 36, 35 37, 37 42°5, 42 | 15—25
2—1°4| 35, 35 36, 35 37, 37 ine 20
1°8 —1:2/35-2, 34°2) 36, 34:5 38. 36 | 44°5, 42 | 15—25)
2-1 —1-4135-5, 34-2] 36, 35 Oe Ca i) VA eee
1-9 —1-4)/35°5, 34°2) 36, 35°2 ate 17—-26| 63
2—1°4/35°5, 34°2) 35°5, 35 44:5, 42 | 18—25
6 Fishery Board for Scotland.
INCUBATION OF HERRING Ova—continued.
|
a TEMPERATURE OF THE WATER.
A sees oy = FLow or WATER.
é (1) eevee lee
® Gravel Glass Tin cooled
= eo ie a i Plates. ; Le eae
= Range in { Max. and “Max. and Max, and | Max. and ~ Nos. | Tin ~ |Uneool’d
4 =f Min. °F. Min. °F. Min. °F. Min. °F. 1 and 2. ‘| Gravel.
| | Secs. | Secs. | Secs.
HpiD-2 1A Reames 186°5,.35:5) ee ‘oases S |) a
46 2—1°2/35°5, 34:2) 36, 35°5 at Ba eg rea ee) ee
AT 2—1 | 35:2, 34 | 36, 34:2 ne 45:5, 42 14,18 ee |
48} 18-1 35, 84 |35'5, 34°2 st 445,38) 18 ae |
49 2—1:2| 35, 34 36, 35 Pi 43°5, 42 | 16—27 ie |
50} 2:2—1:2/35- 5, 34:2) 36, 35°5 a 45°5, 44 17, 36
51! - 6°8 44, 36 44, 66 te 46, 44 9
52 es ma sh e A4°5, 43°5
53 Es Ss P =~ AT, 43
54 fa! S, ahs oe 49,47 |
oD re = | aa a 48°5, 48:5
|
* Water supply stopped for some time during the day.
RESULTS.
The Uncooled Spawn on Gravel.
This spawn was not very clean.
During incubation, the spawn was fully exposed to daylight, but
not to direct sunlight. The eggs detached from the gravel varied in
size from 1°32 to 1:5 mm. in diameter. Eggs which had been stuck
to the gravel, and which had been forcibly detached, had lost a patch
of the outer layer of the zona. This did not appear to exercise any ill
effect. No crystals were observed in this lot of spawn.
The first larva appeared on the 19th day, and larvae were
obtained almost daily up to the 29th day. On the latter date a few
of the eggs still contained embryos.
Spawn Ineubated in the Galvanized Tin.
This lot of spawn was treated with water similar to that supplied
to the uncooled gravel spawn up till the time when the larvee began
to appear, viz.,on the 20th day. Thereafter the water was cooled,
and the incubation-period was, in consequence, extended for an
additional 21 days. The larve hatched out daily from the 20th to
the 41st day. The results in this case were very satisfactory.
The retardation consisted in keeping the developed embryos in the
egg after they were ready to hatch. The result was that many of the
larvee, when they hatched, had already consumed a large portion of
the yolk. On the 40th day three had only a trace of yolk left (fig. 6).
although a fourth had still a fairly large ball of yolk unabsorbed.
A normally hatched larva may be 8 mm. in length: a post-larva
measured 7°5 or 8 mm. The eggs did not seem to have suffered from
the cooling.
The Retardation of the Development of the Ova of the Herring. 7
Diatoms were noticed at different times on the eggs, some of
which became somewhat dirty externally. They were, however,
partly sheltered from the light by being enclosed within the
pattially-closed tin. They did not, therefore, become so dirty with
diatomaceous growth as the other lots of eggs.
Crystals, in some cases in great quantity, were observed in certain
egos. The majority showed none. The crystals were attached to the
zona, sometimes in rosette-form, or even inside the embryo. They
were observed in one of the trunk canals, apparently the gut (fig. 3).
In the embryo, a large corpuscle plugged the heart with each pulsation,
and then receded again (fig. 9). Next day the corpuscle remained
clear of the heart. Crystals were observed in the gut of another
embryo, the heart of which had no plug. One lively embryo had a
huge quantity of crystals attached to the inside of the zona.
Cooled, Spawn.
The gravel spawn examined nine days after spawning seemed to be
in a pretty good condition, but some dead eggs were to be seen. On
the 11th day, the spawn on the glass plates looked well, except where
the eggs were in a thick mass. In such places dead eggs were
observed. Some of them had no doubt been killed by the pressure of
adjacent eggs. Certain eggs were of especially large diameter.
Three that contained embryos showed no crystals, but in certain of
them a granular matter was sticking on the embryo—an unhealthy
sign. An egg, 1°75 in diameter, had an unhealthy looking embryo.
Two eggs measured 1°3 and 1°35 mm. in diameter. Both contained
crystals. In one the crystals were large and few in number; in the
other they were small and fairly numerous.
By the 22nd day a copious growth of diatoms was noticed on the
eggs. The thickly-covered plates did not look so well as those that
had a sparse coating of eggs. Larve began to appear on the 29th
day. On the 42nd day a considerable quantity of dead eggs was
observed. Many appeared to the naked eye of a milky tinge. That
probably indicates that they had died recently. The milky appear-
ance is due to the perivitelline fluid turning opaque. Some of the
ova were yellow-coloured from the coating of diatoms.
On the 5lst day, ripe eggs, containing live embryos, were quite
yellowish. A good proportion of the eggs of one of the good plates
seemed to have hatched.
I examined some eggs that had died recently. In one I could
detect no movement of the embryo. I dissected it out of the egg
capsule. The heart was found to be beating slowly. The embryo
seemed to be perfect. It was, I think, dying from suffocation, due to
the mat of diatoms that covered the zona. The larve which were
obtained on each day from the 29th to the 38th day were prematurely
hatched. They were very small, viz., 4°5-6mm. long. The head was
markedly bent downwards, t.e., much more than in the older larve.
The postlarval body is shorter than normal. Succeeding batches
oradually improved in size. On the 38th day 94 were obtained.
Compared with a larva which had consumed nearly all its yolk, they
were shorter and had the head more flexed. ‘They were pretty lively.
Two measured 6 and 75mm. in length respectively. Thereafter the
8 Kishery Board for Scotland.
following quantities of fry were obtained :—39th day, 120 (20 dead)*:
40th, 250 (20 dead); 41st, 191; 42nd, 335 (100 dead); 43rd, 160
(10 dead) ; 44th, 187 (10 dead); 45th, 98 (4 dead); 46th, 67 (8 dead);
47th, 24 (2 dead) ; 48th, 27 (1 dead) ; 49th, 16 (5 dead): 50th, 14
(4 dead) ; Olst, 8 (3 dead); 52nd, 1 ; 58rd, 1 larva.
After the 39th day the larvee seemed normal. They were shorter
on the whole than the average larva, and they had a comparatively
large amount of yolk still remaining unabsorbed. The heads were
flexed. They wriggled about quite actively with eel-like movement.
On the 47th day two measured 7 and 8 mm. respectively. The head
was only slightly flexed. On the 50th day 10 good fry showed stilla
good quantity of yolk. ‘The heads were slightly flexed.
The hatching of the ova began prematurely in consequence, I
consider, of the decay of the zona, caused by the diatoms attached to
it. The same cause led, in my opinion, to the death, through
suffocation, of many ova. There was also a large quantity of infusors
and many nematodes among the eggs.
The larvee do not appear to have dev eloped much too rapidly. The
cooling was doubtless not sufficiently low. I think a slightly lower
temperature, 34° to 35° F., would not injure the ova and would
probably be sufficient to retard the ova for the requisite period.
Gravel and Glass.
While the spawn attached to the gravel did very well, that on the
glass could not be said to be distinctly inferior. Glass plates are
much more easily handled and with their aid a larger quantity of ova
can be dealt with. The spawn on the gravel was less in quantity,
less crowded, and its situation on small pieces of stone permitted,
possibly, a more effective aeration.
Kxposure to Light: Growth of Diatoms.
A danger which was apparent during this experiment has, I believe,
a greater bearing on the well-being of the ova than their location on
glass or gravel. That is, exposure to light. Light has a great
influence in stimulating the growth of diatoms as Allant and Nelson
show. If deprived of light the culture of diatoms dies off. The
quahty of the water also affects the growth of diatoms. The two
authors point out that in the tank-water of the Plymouth Laboratory
larger and healthier growths of diatoms were got than in water pro-
cured some distance off shore. This fact was ascribed to the greater
quantity of organic matter in the tank-water.
The diatoms which grow on the ova tend to prevent the aeration of
the embryo, and are also, I consider, the probable cause of the
premature escape of the larve by hastening the decay of the zona.
No doubt decay takes place normally during incubation. If that
decay be hastened the embryo may be able to burst its way to
freedom at a smaller size than the av erage.
* The larvee were caught in a trap in which some were killed.
+ ‘The Artificial Culture of Marine Plankton Organisms.” Quarterly
Journal of Microscopical Science, Vol. 55, Pl. 2. June, 1910.
Diatoms attached to the eggs of Lobster, exposed to bright light, caused the
decay of the outer egg-membrane. (Anderton) Report of “Marine Department,
New Zealand, 1908-9. Wellington, 1909.
The Retardation of the Development of the Ova of the Herring. 9
The Current of Water.
I think that the current of water should be strong. It is not
necessary that it be continuous: it may be intermittent. A large
quantity sent through the apparatus at intervals would probably be
more effective than a small continuous current.
The Filter-Barrel.
During the experiment, the filter-barrel, in which was filtered the
water that was cooled, was allowed to work for 40 days. This was
probably an error. Whether it affected the success of the experiment
is donbtful. It would be better to have the filters frequently cleaned.
EXPERIMENTS WITH SPAWN FROM LIVE AND DEAD HERRINGS.
On Galvanized Wire Gauze and Glass Plates.
A number of ripe herrings were put into a herring barrel and sent
to Aberdeen. On arrival all but two were dead. The survivors were
a male and a female. The herrings had been probably not more than
12 hours in the barrel. Four experiments were carried out on March
24th 1911.
(A) Some spawn was obtained from the two live fishes and it was
put on a piece of galvanized wire gauze. The gauze was new, but it
had been for a day or two in running sea-water. The eggs appeared
to do well for a few days. They showed lots of crystals. The eggs
gradually died off, and on the 25th day after fertilization all but three
were dead. The embryo at that time showed black pigment in the
eyes.
* (B) Spawn and milt obtained from dead herrings were put on
narrow-meshed galvanized wire gauze in hatchery water. The eggs
developed for a time, but by the 20th day all but one or two were dead.
(C) Spawn was obtained from a dead fish and put on a glass plate.
This spawn was put into the water in which the herring travelled to
Aberdeen. No fresh milt was supplied to the water. I examined a
drop of the water: tailed sperms were visible, but they showed little
motion. Fertilization ensued, however. Although most of the eggs
died off, two which had embryos ready to hatch were found alive on
the 31st day. A good number of the eggs had died after pigment
had began to show in the eyes of the embryo.
(D) Some spawn and milt were taken from dead herrings and put
on a glass plate in new (hatchery) water. Fertilization took place in
this case also. Many of the eggs had well developed embryos, but
most died before hatching.
The four lots of spawn stood, after being prepared, for some hours
in still water. They were then all put in a revolving tin box set in a
galvanized iron tank. The water supplied to them was cooled. ‘The
temperature is given in the column marked “Tin” (p. 5) from the date
March 26th onwards. One egg which had been in still water all night
showed a large normally segmented disc and a huge quantity of
crystals. Some fry were got from the spawn on the 26th to 31 days
after fertilization.
10 Fishery Board for Scotland.
Milt and Spawn.
Some milt from a dead herring was put into sea-water. I found the
sperms (fig. 7) oscillating vigorously as if anchored by the tail.
Many, however, oscillated very faintly.
No difference was observed between the spawn of the living and
dead herrings.
Some unfertilized eggs, a quarter of an hour after they had been
deposited on the glass plate, exhibited different shapes (fig. 8). Most
of them show an inpushing where they had been pressed by another
egg. No sign of perivitelline space was visible. The eggs were
easily dislodged from the glass. They do not adhere strongly until the
perivitelline space is for med, Three days later these unfertilized eggs
had a fairly large perivitelline space, but they remained dull tinted on
the outside, instead of showing a clear translucent zona.
THE CRYSTALS IN THE EGGS.
The crystals, which were very evident during the two previous
experiments, were found also on this occasion. They are rectangular
(fig. 5), sometimes ending in a tapering oblique point. They may be
fine, needle-like, or fairly thick bars. They appeared in the batches
of eggs which were exposed to the influence of galvanized iron. In
one instance, they appeared within 56 hours after fertilization (fig. 10).
This ege had been in still water in an enamelled bath for a night, and
had probably with it some galvanized gauze.
No crystals were observed in the uncooled eggs on gravel. The
water was delivered to these eggs through large g galvanized iron pipes,
which had been in use for several years. All the cooled spawn
received water through a series of small galvanized iron pipes.
One remarkable fact is that the crystals were not present in all the
eggs of a batch. They may be found (1) on the inside of the zona ;
(2) between the layers of the zona; (5) attached to the yolk or to the
embryo; and (4) within the embryo.
These crystals are soluble in acetic acid, and in sodium hydrate
solution. They are insoluble in water, alcohol, and methvlic ether.
Dr. J. K. Wood, Chemical Department, ‘University College, Dundee,
says that the er ystals, being able to act both as a base and an acid, are
probably formed from proteids by some process of decomposition.
I have came to regard the galvanized iron as, in some measure, the
cause of the formation of these crystals. The galvanized iron becomes
coated with a white incrustation in sea-water. Dr. Wood was not
able to find zinc in solution in the sea-water in which a piece of this
metal had been lying for several days. It seems possible that the
cause of the formation of the crystals is to be found in electrolytic
action. The electric current acting within the eggs on the fluids con-
taining excretory products causes the crystallization. I formerly
regarded the crystals as indicative of deficient aeration, and [I still
favour that view. The deficient aeration resulting in the accumulation
of excretory products in the perivitelline fluid may afford the oppor-
tunity for the action of the current. All the eggs do not exhibit the
crystals. It is possible that the zona may not be acting satisfactorily
from the point of view of osmosis. It is possible that variation may
The Retardation of the Development of the Ova of the Herring. 11
occur in that capsule. As I pointed out above, the diameter of the
zona varies much. In some eggs the two layers of the zona may be
seen separated. In one egg here and there the vitelline membrane
may be made out. Further, the eggs are differently served by the
currents of water.
It is quite possible that the quality of the water at the Laboratory
may be a contributory factor. It is probably charged with organic
matter.
While active embryos are found in eggs containing the crystals, it
is not likely that their presence is an advantage. When the crystals
are formed in a canal in the embryo, they will almost surely prove a
fatal encumbrance.
RECOMMENDATIONS.
If the experiment of transporting the ova of the herring to New
Zealand be made, the following would, I think, be a suitable appa-
ratus. It is shown in plan in fig. 1. It consists of six compartments,
each of which contains a revolving frame. The frame will be able to
carry on its external faces four glass plates, 9 inches by 7 inches. A
section through two of the compartments is given in fig. 1a. A shaft
running longitudinally above the middle of the apparatus would
impart the revolving motion to the frames by means of little belts
(rubber cord.)
The amount of water circulated through the apparatus should be as
large as possible. If iron pipes are used to cool the water it will
probably be better to have ordinary unprotected iron pipes.* In any
case, the pipes and apparatus should be well seasoned, by being
exposed to the action of sea-water, for some time previous to the
experiment being made. ‘The water when it leaves the cooling
apparatus should pass into a reservoir, surrounded by ice. Thence it
should flow through the apparatus. If the water be not used over
again, the waste water can be utilized to cool the mcoming water.
Where the water is to be used over again, a pump will be required to
bring it from the reservoir. A small quantity of freshly-cooled water
should be steadily added.
This apparatus should be provided with lids, and should be kept in
a dimly-lghted apartment.
It is most important to have clean water at all times for the spawn.
This should be carefully arranged when the spawning is taking place,
for mud, etc., adhere readily to the ova. “Wherever necessary, the
water should be filtered through sand. It is hardly possible that all
the eggs pressed on to the plates will live.
Where only a small quantity of cooled water is available, it might
be advisable to have it sterilized. I have not, however, made any
experiments with sterilized water.
Some precautions should be observed when the spawn is being
obtained. Only spawn that runs freely on gentle pressure should be
employed. Milt and spawn should be preferably obtained from living
fishes. The eggs should be arranged thinly on the plate. They
should be protected from being touched after they are on the plate.
The spawn should be brought into moving water as soon as possible.
_ * Vide Davis., ‘‘The Action of Water on Zine and Galvanized Tron.” The
Journal of Chemical Industry. Vol. XVTII., Feb. 28, 1899.
12 Fishery Board for Scotland.
An interval of four to six hours in quiescent water has, however,
usually been given to allow of the ova becoming fastened to the glass.
The glass plates can be put into wooden boxes, each holding
about six plates. The boxes may be put in a herring barrel into a
frame, which can be revolved from time to time. The barrel would,
if necessary, be surrounded with ice during the railway journey.
The spawn should be protected from the light.
For the woodwork, I think coal-tar is a suitable preservative.
PEATE: 1
Fic. 1. Drawing (plan) of apparatus for conveyance of herring Spahite
ae A: Be (section) »
» 2. Drawing of apparatus in which the cooled herring | spawn was kept
during the Spring of 1911.
Enlarged drawing of part of embyro, to show crystals in gut.
Live egg attached to dead egg, showing large number of crystals.
Enlarged drawing of crystal.
Enlarged drawing of anterior end of a larva, which had been retained in
the egg until much of the yolk had been absorbed.
7. Enlarged drawing of a sperm.
» 8. Different shapes assumed by unfertilized eggs when they fell on the
glass plate.
,, 9. Drawing to show the corpuscle which alternately blocked and receded
from the heart of the embryo partially shown in fig. 3.
,, LO. Egg in which erystals had appeared within 36 hours of spawning.
LETTERS USED.
a.—Anus. nt.—Notochord.
er.—Crystal. o.—Outer skin of zona.
de.— Dead egg, pl.—€ plate.
dmf.—Dorsal marginal fin. t.—Tray.
gt.—Gut. | vmf.—Ventral marginal fin.
le.—Live egg. yk.—Yolk.
f ice
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