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Rh Leet: a Wa ae xf Hes ‘ 4 ! rt aire” hi ye Pet) 4 , is { t ' Ls it j vr Vp ta eh, (ns i { nVey) uh ne aa foe, i ly RAS 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. ) 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. Iw 990 20°98 Bl aTe AN a Feo ee Val 5 oY Ko1rfows 20 oe : ha| Aco oe yor = g eo proses aemoeele PEE CAO 200% ata eS Meh Se \ UG \ \wstis \ he ey H.Cc.w. (1312£) 403/46, 500, 4/11, BANKS & CO.LTD. 62. 63. 64 66. 67. 3 “% ’ PAINE, “GET; Sebastes marinus, male, abdomen. Nat. size. female “8 re . 39 9 bop) 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. oa : 7 i . = g a i he e — ~ ~ NN - ~ * ’ - pe ah aaah, cline Bene) oh ‘Bat f u¢ Fig. 7 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. o r a 3 o x se < 0 = 2 o Ki o S % wu z H.C.W. it Fic. 105. 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. H.C.w. (1312€), 403/46. 500. 2/11 BANKS & CO.LTO. 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. To be purchased, either directly or through any Bookseller, from OLIVER & BOYD, Tweeppate Court, EpinpurGH; or WYMAN & SONS, Lrpv., Ferrer Lane, E.C.; or EK. PONSONBY, Lrp., 116 Grarron Srreet, Dusty. PRINTED BY JAMES HEDDERWICK & SONS, LTD., Av ‘‘Tue Citizen Press,” St. Vincent Puace, Guascow. ibe! 5 a Price Fourpence. fine PAGE aM ais Ka A | ret a. a = a a ay: Bean TO “ATA aan. wee chia cae Re ae! coe a , oe Pa ay = f = ‘ ry xr Lf d be i .~< * = ri? nt 4G €: duly suk. ety ATA ta s f / 1a OE df, 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 [1 (ei, ill ¢ ——<—<——— I IA | ccc ic I Ae is NK! le le H.C.W. Figs. I,14,2 are drawn to the Scale -%a inch= Linch. (2aa0€), 10769—231/2. 700. 7/11. BANKS & CO. LTD BL WHO! Library - Serials hans yy MY eet a <3! Panihe ay ne We Re ae a nati S if . 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