bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Adult Digenetic Trematode From an Invertebrate Host:Proctoeces Subtenuis (Linton) From the Lamellibranch Scrobicularia Plana(Da Costa)
Authors: Freeman R. F. H. , Llewellyn J. 
Published: May 2009

The digenetic trematodeProctoeces subtenuis(Linton, 1907) is recorded from the kidney of the lamellibranchScrobicularia plana(da Costa). At Chalkwell in Essex all of nearly a thousandS. planaexamined were found to be infected, as were three of approximately 150S. planaat Whitstable in Kent. The average number of parasites per host was between four and five. NoProctoeces subtenuiswere found inScrobicularia planaexamined from other localities in Essex, Devon, Wales and Suffolk. The environmental conditions of a parasite in the lamellibranch kidney are discussed. It was found that the kidney fluid surrounding the parasites varies in osmotic pressure.The anatomy of the parasite is described. The excretory bladder has a cellular wall, thus disagreeing with the inclusion ofProctoeces subtenuisin La Rue's superorder Anepitheliocystidia. The red colour of the parasite is due to a native haem pigment. The egg capsules are hardened by a quinone-tanning mechanism, but incubation with catechol, protocatechuic acid, and dopa failed to reveal the presence of a phenol-oxidase.The species ofProctoecesare reviewed, and some revisions suggested.P. magnorusManter, 1940 is considered a synonym ofP. subtenuis, and the synonymy ofP. erythraeusOdhner, 1911 withP. subtenuisis confirmed. The differences betweenP. insolitus(Nicoll, 1915) andP. subtenuis, and betweenP. maculatus(Looss, 1901) andP. subtenuis, require re-examination. It is considered thatP. macrovitellusWinter, 1954 should be excluded from the genusProctoeces. A definitive host list ofProctoecesspp. is given.The adult nature ofP. subtenuisfromScrobicularia planais discussed, and it is suggested thatProctoeces subtenuisin the Thames estuary shows an abbreviated life cycle restricted to invertebrate hosts.
The Osmotic Mechanism of the Cuttlebone
Authors: Denton E. J. , Gilpin-Brown J. B. , Howarth J. V. 
Published: May 2009

Experiments are described which test the hypothesis that the cuttlefish controls the relative volumes of gas space and liquid within its cuttlebone by an osmotic mechanism acting across the siphuncular surface of the bone. When the animal is at the bottom of the sea it would maintain the gas space within the cuttlebone by balancing the hydrostatic pressure of the sea by an osmotic force between the liquid within the cuttlebone and the blood.In cuttlefish kept for some weeks in shallow water in an aquarium all the liquid taken from the cuttlebone is almost isotonic with the animals’ blood.In animals recently hauled from the bottom of the sea the cuttlebone liquid is markedly hypotonic to sea water and hence to the blood.These lower osmotic concentrations are given chiefly by reduction in the concentrations of the sodium and chloride ions.After bringing animals up from about 70 m to the surface of the sea the osmotic concentration of the cuttlebone liquid rises from about 75% of sea water some 40 min after starting to haul the trawl, to about 97% of sea water 6 h later. Extrapolation back to the time at which hauling began gives a concentration of salts close to that predicted by the osmotic hypothesis.Whilst the cuttlebone liquid is increasing in ionic concentration the liquid deeper in the cuttlebone is hypotonic to that just inside the siphuncular surface. This is explained in terms of the slowness of exchange of salts along the narrow channels between the lamellae of the cuttlebone.
The Bottom Fauna of the English Channel
Authors: Holme N. A. 
Published: May 2009

A survey has been made of the bottom fauna inca. 10–50 m along the south coast of England, using a modified anchor-dredge. Particular attention has been paid to the molluscs (both living and dead) and to the echinoderms, only larger or more conspicuous members of other groups being identified.Within the Channel there are considerable variations in temperature and other hydrographic conditions, and these are discussed in relation to their possible role as limiting factors in distribution. The fauna and bottom deposits of the different areas covered in the survey are briefly described.Distribution trends are classified as:(1) Species generally distributed in the Channel. This is the largest group, and includes three species reaching their northern limits in British waters.(2) Species confined to the western parts of the Channel.(a) Western species. Four or five species common at Plymouth in the 1920's, but now absent or very rare. Small numbers are found today only off the south Cornish coast, and those which occur in the North Sea are restricted to the north-western areas. Apart from one species, these forms are not at their geographical limits in the English Channel, and their occurrence may be partly related to the presence of ‘western’, but not necessarilySagitta elegans, water.(b) Cornubian species. These are near the northern end of their range, and occur quite commonly off the south Cornish coast, becoming progressively less common farther up-Channel. It is suggested that their distribution is related to an intolerance of the lower winter temperatures in the more eastern part of the Channel.
On the Biology of Calanus Finmarchicus XII. The Phosphorus Cycle: Excretion, Egg Production, Autolysis
Authors: Marshall S. M. , Orr P. , Conover R. J. 
Published: May 2009

It is shown that equilibrium of 32P throughout the body of Calanus is reached only after a feeding period of about a week. The time required to liberate by excretion the amount of P present in a Calanus is about 20 days. Fed Calanus excrete at a higher rate than starved. The implications of excretion in feeding experiments using 32P is discussed.There are large differences in the total P content of individual Calanus. Figures are given for ripe and unripe females, fat and lean Stage V, and eggs. A high percentage, up to 55% of the total P, may be lost by excretion during starvation.A high proportion of the P in the food assimilated (up to 70%) may appear within a week as eggs laid.Liberation of P from dead Calanus is very rapid and is almost complete in three days.The relation of excretion and autolysis to the P cycle in the sea is discussed.
Formation and Regeneration of Abnormal Cells of the Marine DiatomDitylum Brightwellii(West) Grunow
Authors: Canterford G. S. 
Published: May 2009

Heavy metals, as well as affecting the growth rate and photosynthesis of algae, have a considerable effect on the size and morphology of algal cells (see, for example, Erickson, 1972; Nuzzi, 1972; Davies, 1974; Kayser, 1976). Changes in the colour of algae in the presence of heavy metals have also been observed (Greenfield, 1942). At metal concentrations resulting in total growth inhibition of algae the cells, although abnormal, are not necessarily dead (see, for example, Nielsen & Kamp-Nielsen, 1970; Erickson, 1972; Nuzzi, 1972; Blankenship & Wilbur, 1975).In heavy-metal toxicity studies withDitylum brightwellii(West) Grunow (Canterford & Canterford, 1979) it was observed that low concentrations of ethylenediaminetetraacetic acid (EDTA) and toxic concentrations of several heavy metals resulted in the formation of abnormal cells. In the present paper factors affecting the formation of abnormal cells are discussed. Experiments were carried out to establish whether or not these abnormal cells could be regenerated.
The Life History of the Cirratulid Worm, Cirriformia Tentaculata, on an Intertidal Mudflat
Authors: George J. D. 
Published: May 2009

The seasonal fluctuation in numbers of C. tentaculata was investigated from
December 1959 until February 1962. The lowest numbers were recorded in April followed by a rapid increase in numbers during May. The magnitude of the increase varied from year to year, as also did the number of peaks that occurred during the summer months.The worm was shown to have an extended breeding season from the end of March to September during which several spawning ‘bursts’ took place. Experiments suggest that some spawning may occur when the mudflat is inundated by the rising tide, although spawning was not observed in the field.The population of C. tentaculata exhibited an annual cycle of growth which was influenced by the seasonal variation in temperature. Laboratory observations suggest that a temperature of about 20° C is optimal for the growth of young worms. The growth rate (8 mm/year) is slow compared with that of other polychaetes.It is tentatively concluded from the field mortality data that between 10 and 16 % of animals survive to an age at which they are sexually mature; between 6 and 8 % of each generation reach an age of 15 months. Causes of mortality in the population are briefly discussed.
The Neurosecretory System of the Vena Cava In Cephalopoda I.Eledone Cirrosa
Authors: Alexandrowicz J. S. 
Published: May 2009

Nerves known to supply the anterior part of the vena cava in Cephalopoda have been found to belong to a special system for which the term ‘neurosecretory system of the vena cava’ (NSV system for short) is proposed. InEledone cirrosathis system consists of neurons whose cell bodies are aggregated: (a) in the visceral lobe in a layer termed the NSV layer; (b) in the ganglionic trunks continuous with this layer and associated with nerves arising from the visceral lobe—there is on each side a ‘lateral NSV trunk’ accompanying the nervus infundibuli posterior, and a ‘medial NSV trunk’ accompanying the nervus visceralis. Each of these trunks in its further course separates from its nerve and runs far in the caudal direction diminishing in thickness and giving off sideshoots of irregular shape which end blindly in the loose connective tissue and show no connexions with any organ.The NSV layer and trunks consist of unipolar nerve cells of small size and uniform appearance. Their very thin axons unite in bundles which form nerves running to the vena cava. The total number of neurons of the NSV system, approximately estimated, must be over two millions. The disposition of the elements of this system is peculiar in that the axons of the cells situated in the caudal prolongations of the ganglionic trunks must run far rostralwards until they reach the nerves to which they contribute.The nerves entering the vein penetrate through its muscle coat and form a network under the endothelial lining of the vein; this continuous neuropile layer extends from the anterior end of the vein to the entrance of the vena hepatica; all this part of the vein has on its inside longitudinal ridges formed by the uneven thickness of the neuropile layer.
The Integumentary Mucous Secretions of the Ophiuroid Ophiocomina Nigra
Authors: Fontaine A. R. 
Published: May 2009

The general histology of the integument of the ophiuroid Ophiocomina nigra is outlined. Two types of integumentary mucous glands are described in detail for the first time. The first is a multicellular gland, the basal end of which is located deep within the calcareous layer of the integument. The source of the secretion is a variable number of nuclei embedded in a common cytoplasmic mass filled with fine basiphil granules. These cells contributed their secretion to a duct which pursues a tortuous course through the integument. The ducts frequently branch and anastomose so that any one exit pore may extrude mucin derived from a number of separate, polynuclear sources. The structure so formed is, thus, a massive, multicellular gland. Histochemical studies demonstrate that the mucin is a highly sulphated acid mucopolysaccharide. The second type of mucus-secreting unit is a unicellular gland usually located superficially in the calcareous layer or sometimes restricted to the epidermis and distributed universally over the body. The secretion product of these cells is shown histochemically to be a simple acid mucopolysaccharide. The mucin secreted by the tube-foot glands is demonstrated also to be a highly sulphated acid mucopolysaccharide.The function of these secretions has been investigated to some extent. The massive glands secrete only under conditions of alarm and it is suggested that this mucus serves as a defence against predation. The unicellular glands secrete in a periodic fashion correlated with the act of feeding. This secretion is probably utilized in a suspension-feeding mechanism.
The Chorioidal Tapeta of some Cartilaginous Fishes (Chondrichthyes)
Authors: Denton E. J. , Nicol J. A. C. 
Published: May 2009

1. A study of the histology of the eyes of some cartilaginous fishes has been made with special reference to their reflecting tapeta.2. The rate and way in which the pigment in the melanophores spreads over the reflecting cells of the tapetum ofSqualus acanthiaswhen it is lightadapted are described.3. The reflecting plates in the tapeta are about parallel to the plane of the retina in the centre of the eye, but as we move towards the periphery they become more oblique, until near the ora they are almost perpendicular to the plane of the retina. It is shown that when we take account of the way in which the pupil limits the light which can reach the retina in all these situations the plates are arranged to be roughly perpendicular to the incident light. They reflect light either back through the pupil or on to the very black inside surface of the iris and do not scatter it to other parts of the eye.4. The reflectivity of tapeta for various angles and various wave-lengths of light has been found by several different methods, and a new and simple way of measuring the reflectivity of natural tissues is described. For the blue and green lights which will be those reaching the eye in life the reflectivity is very high, over 80%, and so approaches that of a good metallic mirror.5. The external segments of the retinal rods of cartilaginous fishes which have well-developed tapeta are only about half as long as those of other fish living in the same environment, and the retinal optical densities of photosensitive pigments in these fish are only about a half of those of fish without reflecting tapeta.
Aspects of the Biology of Laminaria Hyperborea III. Survival and Growth of Gametophytes
Authors: Kain Joanna M. , Jones N. S. 
Published: May 2009

The lower limit of the Laminaria hyperborea (Gunn.) Foslie zone is probably not always determined only by lack of sufficient light, even when a suitable substratum is present (Kain, 1962). It also appears that the establishment stage is critical although growth conditions deteriorate with depth (Kain, 1963). It therefore seemed desirable to determine exactly what the light requirements of the various different early stages were, and relate these to what could be found out about the light penetration in the natural habitat. The effect of temperature on these stages is also of interest, in relation to the seasonal cycle as well as to the geographical distribution of the species. In this study two different techniques were used: culturing the gametophytes on cover-slips and also studying changes in oxygen concentration as measured by the Winkler method.The gametophytes of the different members of the Laminariales show a similar general course of development. A zoospore from a fertile frond of a Laminaria plant loses its motility, rounds off, swells and produces a tube with another sphere at the end into which all the cell contents pass (Killian, 1911). This process can be carried through in the dark but further development depends on light (Schreiber, 1930). In this genus the gametophytes are dioecious (Sauvageau, 1918; Williams, 1921) and equal numbers of male and female plants are produced (Schreiber, 1930). The female gametophyte may become fertile before dividing further (Sauvageau, 1918), resulting in a single egg, or may form a luxuriant filamentous structure which may produce many oogonia over a period of time (Ikari, 1921; Myers, 1925; Schreiber, 1930).
Experimental Studies of Plankton Luminescence
Authors: Hardy A. C. , Kay R. H. 
Published: May 2009

Experimental studies of plankton luminosity have been made with specially designed photomultiplier equipment; this records (on a Servograph Recorder) the flashes given off either by a sample of plankton or by individual animals placed in a container in a dark observation chamber. The apparatus is described.Apart from preliminary laboratory records on the flashing of Beroë, Pleurobrachia and Pyrosoma, and record of the general luminosity in the sea at a depth of 62 m (made with an underwater version of the apparatus), the main work has been a laboratory study of the luminescence of dinoflagellates and of the euphausiacean Meganyctiphanes norvegica.The dinoflagellate experiments showed the inhibiting effect of light, both natural and artificial, on luminescence, and the stimulating effect of mechanical disturbance which may override the former inhibition. A rise in temperature increased luminosity and cooling reduced it. A difference in the pattern of the luminosity of plankton samples containing dinoflagellates was shown by the introduction of actively swimming animals of different kinds. The dinoflagellates in the samples were mainly Peridinium depressum, Ceratium horridum and C. tripos var. balticum.The Meganyctiphanes experiments showed a spontaneous flashing in seventeen out of twenty-seven tests and in one test the animals maintained such activity for the greater part of a 24 h period. In addition to their bright flashing, the photophores would at times keep up a dull glow for long periods (especially see the observations of F. Körte in the Appendix). Spontaneous flashing does not only occur in the breeding season as had been suggested by Mauchline (1960).
The Structure, Ciliation and Function of the Lip-Apparatus of Lima and Pecten [Lamellibranchia]
Authors: Gilmour T. H. J. 
Published: May 2009

The structure and ciliation of the lip-apparatus of two species of Lima—L. hians (Gmelin) and L. excavata (Fab.)—and one species of Pecten—P. maximus (L.)—is described.It is suggested that the lips of these three species of bivalves have been hypertrophied (and in one case partially fused) in order to retain particulate material being carried from the ctenidia to the mouth while at the same time allowing the escape of water currents, generated by the ciliary tracts of the ctenidia and palps, from the proximal oral grooves. Such water currents must emerge from between the lips of all bivalves but do not usually interfere with the passage of particulate material. In the Limidae and Pectinidae, these water currents have been intensified by the reduction of the anterior regions of the mantle cavity. Since this change in the proportions of the body can be correlated with the evolution of the monomyarian condition in the Anisomyaria,
it is postulated that the lips of all monomyarian Anisomyaria will be similarly hypertrophied.
External morphology of the choanoflagellateSalpingoeca gracilisJames-Clark
Authors: Thomsen Helge Abildhauge 
Published: May 2009

In his search for evidence illustrating the botanical/zoological affinities of the sponges (Porifera), James-Clark (1867) studied a number of colourless flagellates. The genusSalpingoeca(Craspedophyceae, Christensen, 1962; cf. Chadefaud, 1960) was thus erected to comprise certain solitary, lorica-dwelling organisms, characterized by a single anterior flagellum encircled by a ‘filmy, membranous, colourless collar’ (James-Clark, 1867).About fifty species (approximately twenty marine) are at present allocated to this genus, provided it is defined as e.g. by Norris (1965) and Bourrelly (1968) (i.e. includingLagenoecaKent andPachysoecaEllis).
The Distribution of Iron in the Waters of the Western English Channel
Authors: Cooper L. H. N. 
Published: May 2009

With 2:2′-dipyridyl as reagent for reducible and total iron, determinations were made on samples from the western English Channel at midwinter 1946–47, at the time of the maximum of phosphate, and also in July 1936.The midwinter results have been treated statistically and the errors of analysis assessed.Unlike phosphate and nitrate, much of the inorganic iron occurs as particles of fair size, distributed at random in the water. In winter there is no statistically significant difference between the total iron content of samples drawn from 0·5,5,25 and 50 m. depth, the grand mean and standard deviation for the whole area being 0·25 ± o·11 mg.-atom/m.3. The reducible iron for the same depth range and area was 0·19 ± 0·14 mg.-atom/m.3. There appears to be about 0·06mg.-atom/m.3 of iron which is reasonably highly dispersed and not determinable until the water has been oxidized with bromine.In the bottom layers of water, although the reducible fraction differs little from the overlying layers, the total iron shows a very much greater mean value and variance.The very low content of total and reducible iron and of particulate ferric phosphate in bottom water at a position 49° 30′ N., 5° 00′ W. has been provisionally attributed to removal by a dense bed of suspension feeders, possibly the mollusc Pinna.By a statistical examination of the analytical results it has been deduced that the particulate fraction in the upper 50 m. was distributed on an average amongst about 45 particles per litre, each containing about 0·24μg. Fe and with a diameter of about 160μ. This result has been compared with data on the distribution of iron in plankton organisms.As a statistical average waters richer in phosphate were also richer in total iron, the atomic ratio Fe/P being about 0·57.In July 1936 the ‘elegans’ water to the westward was much richer in both phosphate and total iron than the more eastern mixed water containing Sagitta setosa. The results agree well with the conclusions drawn from the cruises at midwinter 1946–47.In 1933–34 concentration of iron was frequently observed in the surface layers; in 1946–47 it was not. In the earlier work the surface film was always cut and included in the sample, in the later it was not. The probable amount of a surface unimicellar film of electropositive unprotected ferric hydroxide has been calculated and agrees well with observation.Particulate ferric phosphate was found to the extent of about 0·06 mg.- mols/m.3 This appears to increase towards the bottom.The success of the work at Newlyn in January 1947 owes much to the willing co-operation of Capt. Creese and the crew of R.V. Sabella under very adverse weather conditions. To Mr P. G. Corbin grateful thanks are due for undertaking single-handed the supervision of all the scientific work at sea on stations never more than two hours apart for two or three days on end. The statistical development would not have been possible without the unstinted assistance of Mr G. M. Spooner.
Phosphate and Fisheries
Authors: Cooper L. H. N. 
Published: May 2009

Landings of the spurdog, Squalus acanthias, at Mevagissey reflect the changes in phosphate at the neighbouring International Hydrographic Station Ei.It is suggested that commercial landings of rays and skates ought to follow major changes in nutrient content of the overlying water with a time lag of some years. Fishery statistics for English Channel ports support this view. The dependence of the bottom in-fauna upon the fertility of the overlying water is also discussed.Proposals to improve commercial fisheries by artificially fertilizing considerable areas of the open sea are critically examined. Such artificial enrichment is considered to be grossly uneconomic unless fishing becomes pisciculture in which weeding of unwanted algae and control of unwanted pests—competing predators and parasites—is undertaken.