bluuebunny/crossref_metadata_2025_split huggingface dataset:
Defaecation in Relation to The Spontaneous Activity Cycles ofArenicola MarinaL.
Authors: Wells G. P. 
Published: May 2009

The behaviour of lugworms in sand was studied by recording kymographically the water movements through their burrows and observing the timing of defaecation. The worms ranged in weight from 2 6 to 186 g. Three types of apparatus were used, differing in the amount of space allowed to the worms.The worms often traced a characteristic pattern described elsewhere, consisting of regularly spaced diphasic excursions of the irrigation graph with a defaecation on the apex of each first phase. The interval between excursions was about 15–20 min. for worms weighing about 3 g. and increased with size to about 40 min.The worms sometimes traced similar periodic bursts of irrigation activity without defaecation.Many of the tracings were confused in pattern. The worms often defaecated—sometimes sporadically, sometimes at regular intervals—in the absence of the characteristic diphasic excursions. Restriction of a worm to a small space appears to favour the production of confused tracings.The relation between the irrigation patterns and the timing of defaecation is discussed.
Comparison of the Different Methods of Estimating Nanoplankton
Authors: Dorothy Ballantine  
Published: May 2009

Six methods for estimating the numbers of nanoplankton organisms in sea water have been compared. Of these, centrifugation of a living sample, followed by counts of the numbers of organisms in the concentrate, appears to be the most satisfactory method from all points of view. The method is rapid, simple to operate, and gives a result which is strictly comparable with results from counts made under dark-ground illumination of unconcentrated samples, and from counts after concentrating with niters. By this method the organisms counted can usually be assigned to the class and order to which they belong, even if their systematic position cannot be determined more definitely.The use of species-pure cultures is a necessary adjunct to the direct examination of sea-water samples when studying the distribution, abundance, and annual fluctuations of nanoplankton, as so little is known of the systematics of these organisms.
The Feeding Habits of Plaice Post-Larvae in the Southern Bight
Authors: Shelbourne J. E. 
Published: May 2009

An examination was made of the stomach contents of plaice post-larvae taken from the Southern Bight spawning ground in the spring of 1950. They were found to be feeding mainly on a soft-bodied prey, which left characteristically shaped faecal pellets and an undigested matrix vesicle as the only evidence of its nature. Pellets from the post-larvae compared closely in shape with those of Oikopleura dioica, found in the plankton of the spawning area during the period of post-larval development.In 1951, undigested Oikopleura were seen in the oesophageal regions of a few dissected specimens, in addition to typical indigestible remains in a large proportion of the total feeding post-larvae examined.Records for 1946 suggest a similar exploitation of the Oikopleura population by plaice post-larvae, although the phenomenon was not repeated in 1947, when inclement weather may have interfered with the annual outburst of this prey.The phenomenon of food selection by plaice post-larvae is discussed, with special reference to the part that vulnerability may play in limiting the number of species of prey available as food.A feature of this and other investigations on post-larval feeding, was the occurrence of a high proportion of empty stomachs. An experiment designed to test a regurgitation hypothesis, revealed the existence of a marked diurnal pattern of feeding activity, apparently influenced by light conditions. The importance of light in feeding behaviour was confirmed by tank experiments. In this investigation a large proportion of the empty stomachs encountered can be explained by reference to diurnal fluctuations in feeding activity, supporting the view that plaice post-larvae are visual feeders.
The Settlement of Ophelia Bicornis Savigny Larvae The 1952 Experiments
Authors: Wilson Douglas P. 
Published: May 2009

Previous conclusions that it should be possible to forecast the intensity of settlements which will be obtained in fifty-fifty mixture of two sands, provided the relative attractiveness or repellence of each component is known, were fully confirmed. The results of these mixture experiments agree with the classification of sands as attractive, neutral or repellent.It is shown that an attractive factor is capable of transference, in sea water, from fresh Bullhill Bank sand to acid-cleaned quartz sands, to calcareous oolitic sand and to an artificial sand of fused alumina. The attractive factor is present in water in which fresh Bullhill Bank sand had been shaken.A similar transference of a repellent factor from fresh Salthouse Lake sand is not so clearly demonstrable. Water in which fresh Salthouse Lake sand has been shaken appears to contain the attractive factor. Thus both attractive and repellent factors may be present in Salthouse Lake sand.Activated charcoal stimulates larvae to settle and metamorphose, but needs to be in granular form, or associated with neutral grains, to exert its full influence. The charcoal contains copper in minute proportion, but whether this has any significance for metamorphosis is undetermined.The grade of a sand was again shown to be a settlement factor of some importance. The most attractive grain sizes appear to be those of which the bulk of the Bullhill Bank surface sand is composed.Analysis shows that the surface sand of Salthouse Lake (St. II) contains some three times the organic nitrogen content of the surface sand of the Bullhill Bank.
Marking Fish with the Electric Tattooing Needle
Authors: Hickling C. F. 
Published: May 2009

Most fishery biologists have heard from time to time of experiments on marking fish by tattooing identification marks on them. The present usual methods of marking fish by attaching marks externally to the gill-cover, caudal peduncle, or other part of the body, have the disadvantage that a certain number of the marks are lost, and this uncertainty bedevils all those marking experiments designed to show rates of mortality or rates of capture.Yet the only reference in the literature known to me is a very short paper by Gandolfi-Hornyold (1929). His most successful experiment consisted in marking six silver eels on the light ventral side withIndian ink (encre de Chine) introduced in the oriental fashion by a bundle of needles. Five of the six fish were alive some 6 weeks later with the marks as clearly legible as when first made. But I know of no further developments of this techniqueIn August 1939, I made some experiments at the Plymouth Laboratory, by the courtesy of the late Director, Dr Kemp, F.R.S., and with the help of the staff, to all of whom I would express my thanks. Some thirty-two plaice, two soles, and twenty-five rays were placed in one of the big outdoor tanks for the experiments, and were all in good condition, though they had not been fed and were certainly overcrowdedThe electric tattooing needle used was bought from a professional tattooist, who also gave me a brief lesson on his art. In principle the needle is a small vibrator run from an ordinary torch battery.
Note on Selective Feeding by Calanus
Authors: Harvey H. W. 
Published: May 2009

The rates at which Calanus finmarchicus eat both carmine particles and the diatom Nitzschia closterium have been investigated by Fuller & Clarke (1936) and Fuller (1937). They found that the number of Nitzschia or of carmine particles, eaten by a Calanus in unit time, was proportional to the concentration of Nitzschia or of particles in the water. Lucas (1936) also found that Neomysis and Eurytemora ate Nitzschia at rates which were roughly proportional to the concentration of diatoms in the water over fairly wide limits.During 1935 I had made, as part of another investigation, three experiments on the rate at which Calanus eat diatoms of larger size. This happened much more rapidly than Fuller found to be the case with suspensions of Nitzschia. Meanwhile Lowndes (1935) had concluded, from direct observations, from the anatomy of their mouth-parts and from observations by Lebour and Marshall, that Calanus should be able to catch and select food. He concludedthat Calanus does not depend entirely upon its (automatic) filtering mechanism for all the food it obtained.The quantitative data which I had collected in these three experiments, in conjunction with those published by Fuller & Clarke (1936,1937), were suitable for examining this contention. They suggested that the animal when fed with diatoms of moderate size selected by catching the species it preferred, while it automatically filtered the minute Nitzschia. With these possibilities in view, experiment N 90 was made in order to link up the three experiments with the numerous experiments made by Fuller (1937).
The Supply of Iron to Diatoms
Authors: Harvey H. W. 
Published: May 2009

The nature of iron occurring in sea water, and its utilization by diatoms, is discussed.Diatoms in the sea obtain many thousand times more iron than calculation shows they can obtain by diffusion of iron ions from the surrounding water.Evidence is presented that ferric hydroxide is readily adsorbed on the surface of diatoms.It is shown that colloidal and larger particles of ferric hydroxide or phosphate can be utilized by, and support the growth of diatoms.Experiments show that the diatoms Nitzschia closterium and Lauderia borealis require, for continued growth, a very small quantity of iron compared with that found on, and in, diatoms taken from the open sea.It is contended that iron hydroxide adsorbed on diatoms is in contact with an interface where its solution, and subsequent passage into the cell, is probable.
Oxygen Production by the Diatom Coscinodiscus Excentricus Ehr. in Relation to Submarine Illumination in the English Channel
Authors: Jenkin Penelope M. 
Published: May 2009

1. A method, due to Poole & Atkins, is described for computing the total available energy at any depth in the sea, in joules or g.-cal.2. The oxygen production of pure cultures of the diatom Coscinodiscus excentricus Ehr. was measured by the Winkler method after exposure of the diatoms in bottles at known depths in the sea. 3. The results of simultaneous measurements of oxygen production and of energy are given for 6 days in July and August 1933 and 1934.4. Factors, other than light, that might affect the rate of oxygen production in the experiments are discussed and shown to be negligible. It is assumed that diatoms can use energy for photosynthesis equally well in all parts of the visible spectrum.5. When the energy flux during the exposures is less than 75 joules or i-8 g.-cal. per cm.2 per hr., the oxygen production is directly proportional to the energy. The utilization of the available energy then amounts to about 7%.
Relation of Bacteria to Diatoms In Sea Water
Authors: Waksman Selman A. , Butler Margaret R. 
Published: May 2009

1. Dead marine diatom plankton was found to undergo rapid oxidation and decomposition when added to fresh sea water. This was measured by oxygen consumption, nitrogen liberation, phosphate regeneration and bacterial multiplication.2. Living diatoms added to sea water and placed in the dark continued to absorb oxygen; they were rather resistant to bacterial attack.3. Diatom-rich marine plankton also absorbed oxygen, while the phosphorus was gradually regenerated. The bacteria did not increase in numbers in correspondence with the oxidation of the fresh diatom material.4. When sea water in which photosynthesis was allowed to proceed for varying periods of time was placed in the dark, rapid oxidation of the freshly synthesized material took place, as indicated by oxygen consumption and phosphate liberation. Although there was a greater number of bacteria in the water in which photosynthesis took place, the oxidation of the fresh diatom material was not accompanied by any large increase in bacteria; in fact a decrease in numbers was frequently observed.
The Triradiate and other Forms ofNitzschia Closterium(Ehrenberg) Wm. Smith, FormaMinutissimaof Allen and Nelson
Authors: Wilson Douglas P. 
Published: May 2009

1. The natural history in culture of the species ofNitzschiaoriginally isolated from the sea by Allen & Nelson (1910) and grown at Plymouth and elsewhere ever since has been studied. It is shown that three main types of cell exist: normal with two arms (rostra), triradiate with three arms and ovals with none. Both normals and triradiates produce ovals by division, and the ovals so produced can multiply to form further ovals, or can grow either two or three arms, generally two, to form normal or triradiate cells.2. Ovals are more readily produced under good lighting conditions than under weak illumination.3. The cell wall is very lightly silicified, and the cells, unlike those of most diatoms, can elongate without auxospore formation. The maximum, and with it apparently the average, cell size of successive subcultures is variable.4. When triradiates are present they may, and frequently do under good cultural conditions, multiply faster than normal cells and finally may almost completely dominate the cultures. Now and again a proportion of the triradiate cells shorten one arm and gradually pass, during successive divisions, into the normal condition. There is a greater tendency for this process to take place in the autumn than at any other time. There was a notable instance in November 1941 when several cultures at Plymouth and at Hull simultaneously produced normals by this method on an extensive scale.5. There is evidence that under unfavourable cultural conditions triradiates tend to be eliminated.6. A cruciform type of cell has appeared occasionally in several cultures, but it has not been possible to obtain pure cultures of it, for the type appears to be somewhat unstable and readily reverts to the other forms. It has, however, persisted for a long time and for very many generations.7. It is shown that the triradiate type occurs in nature, and there is no reason to suppose that it is an abnormal form due to culturing.8. The nomenclature is discussed and it has been decided for the time being to retain the name Allen and Nelson originally gave to it, although there is a possibility that it is a species separate fromNitzschia closterium(Ehr.) W. Smith.
The Utilization of Organic Phosphorus by Phytoplankton
Authors: Chu S. P. 
Published: May 2009

Cultural experiments were made with marine organisms in enriched crude sea water and in bacteria-free cultures with the phosphorus supplied in different forms. It was found that pyrophosphate cannot be utilized as a source of phosphorus as effectively as orthophosphate by the organisms cultured, i.e. Phaeocystis Pouchetii, Skeletonema costatum and Nitzschia closterium. Growth of Phaeocystis Pouchetii was a little better and lasted longer when phytin was supplied to natural sea water as a source of phosphorus than when orthophosphate was supplied. Phytin can also support a growth of Skeletonema costatum and Nitzschia closterium as good as, or a little better than, orthophosphate.The organic phosphorus compounds used in these experiments were found to be broken down into orthophosphate in natural sea water. In bacteria-free cultures phytin and glycerophosphoric acid can be effectively used as such by Nitzschia closterium forma minutissima as a source of phosphorus, while sodium nucleinate and lecithin can not be effectively used as such. The organic phosphorus dissolved out from the blades of Laminaria can also be utilized by this diatom as effectively as orthophosphorus.It would seem, therefore, that not only the dissolved orthophosphate as generally assumed, but the dissolved organic phosphorus in the sea may also be absorbed and utilized by plants.
A Note on the Capture of Prey bySepia OfficinalisL.
Authors: Wilson Douglas P. 
Published: May 2009

There are various short and incomplete accounts of the capture of prey bySepiascattered throughout the literature (Grimpe, 1928; Hertling, 1929; Holmes, 1940, are all typical and fairly recent), but I have not found any really satisfactory figures. Those I have seen are little better than rough sketches (Grimpe, 1928, p. 372; Naef, 1923, text-fig. 304b; Tompsett, 1939, plate i, fig. 2) and there do not appear to be any photographs at all. A few observations, and some photographs I have taken recently should therefore be of interest, especially as the photographs reveal some points that do not appear to have attracted attention previously. The final stages of the capture take place so rapidly that the eye fails to observe the details, whereas photographs can be studied at leisure afterwards.The specimen ofSepiathat forms the subject of these pictures was of medium size with a shell about 12 cm. long. It had been living in a tank, with others of about the same size, for several months, during which time it had been fed on living prawns. It was photographed in mid-November when the water temperature was 12.5° C. (in a later paper I shall show that below about II° C.Sepiaoften ceases to feed). The photographs were taken by flashlight on two evenings between 7 and 8.30 p.m., the tank being lit, for viewing purposes, by a 100 W. bulb in a reflector above one end (the left side in the pictures). Each photograph was taken at sec. with one Baby Sashalite bulb and a synchronizer of my own design, the shutter being released electrically.
On the Development of Muggiaea Atlantica Cunningham
Authors: Russell F. S. 
Published: May 2009

In September 1937 Muggiaea atlantica Cunningham was very abundant off Plymouth. The presence of large numbers of eudoxids in the plankton afforded an opportunity to rear the early stages of this siphonophore. The development of M. kochi (Will) was worked out by Chun (1882, 1913), and he also described the eudoxid of that species. The eudoxid of M. atlantica has, however, never been described for certain. The allocation of eudoxids collected in the plankton to their respective species is necessarily fraught with uncertainty when more than one species is present. Throughout the whole of September 1937 M. atlantica was the only species of siphonophore to be found off Plymouth, and there can be no reasonable doubt that the eudoxids described below belonged to that species and that the development of the early stages from their eggs is that of M. atlantica.For the terminology used in the description of the eudoxid I have followed Totton (1932), to whom I am grateful for helpful advice.The EudoxidThe bract (Fig. 2 a) is cone-shaped with a broad flat suture running from its apex to the base. The edges of the suture are raised into a slight flange. The right edge is continued downwards into a sweeping curve while the left edge cuts away horizontally at its lower end; the bract is thus asymmetrical. There is a slight cavity on the lower surface in which the somatocyst is centrally placed. The general form of the bract can also be seen in the different views of the whole eudoxid given in Fig. 1.
The Ecology of the Tamar Estuary I. Introduction
Authors: Hartley P. H. T. , Spooner G. M. 
Published: May 2009

During 1936 and 1937 extensive physical and faunistic studies of the Tamar Estuary were made by several workers at the Plymouth laboratory. These investigations, though conducted independently and with different immediate aims, proved to have considerable bearing on one another, and each worker benefited by occasions for co-operation. As the work proceeded it became clear that one of the most important aspects of each investigation was the bearing it had on the balance of life in the estuary as a whole. It was decided to publish the results of these studies in a series of papers in which each contributor should lay due emphasis on data having possible bearings on the problems studied by the others, so as to present as complete a picture as possible.Studies have been made of salinity, temperature, penetration of daylight, macro- and micro-fauna of the intertidal zone, the sessile flora and fauna of the buoys, the fishes and their food, and the birds which frequent the flats and channels. Other studies are contemplated. In the work on light penetration and on quantitative estimates of the fauna of the mud-flats, no comparable data have hitherto been procured in this country.The Tamar is the largest of the rivers which flow into the west end of Plymouth Sound. It is tidal for nearly 19 miles (30 km.) of its course. Rather over 3 miles (5.5 km.) from the sea it is joined by the River Lynher to form the Hamoaze, an estuary common to the two rivers.
The development and early stages of the ascidian Pyura squamulosa (Alder)
Authors: Millar R. H. 
Published: May 2009

In the family Pyuridae the larval and post-larval stages are known only in Halocynthia pyriformis (Rathke) and Boltenia echinata (L.). Berrill (1948) has pointed out that this is the least specialized family of the Pleurogona and that its larvae are therefore of particular interest.On 1 August 1950 specimens of Pyura squamulosa (Alder), up to 36 by 30 mm., were collected from boulders at low-water level in the Sound of Kerrera, Argyll. They were taken on the following day to the Marine Station, Millport, and there kept in running sea water until 4 August, when artificial fertilizations were carried out.
Notes on the reproduction and early development of the cirratulid Tharyx marioni (St Joseph)
Authors: Dales R. Phillips 
Published: May 2009

The larval development of the Cirratulidae is not well known, although an account of the development of Raphidrilus nemasoma Mont, was published by Sokolow in 1911 (under the name of Ctenodrilus branchiata), and of Audouinia tentaculata (Montagu) by Wilson in 1936. Apart from these two publications, only scattered observations may be found in the literature, and these are listed by Wilson (1936). Unfortunately, attempts to rear the larvae of Tharyx marioni (St Joseph) beyond the hatching stage have failed, and as it seems unlikely that further data may be gathered for some time, such results as have been obtained are presented here.The main points of interest in the development and reproductive habits of T. marioni are: (i) the adults are atoquous; (ii) the eggs are comparatively large and yolky, and unlike Audouinia tentaculata, the pelagic stage is omitted; and (iii the larva on hatching is achaetous, as in other cirratulid larvae.
A new species and genus of Brachiopoda from the western approaches, and the growth stages of the lophophore
Authors: Atkins D. 
Published: May 2009

A new species and genus of brachiopod has been dredged by R.V.‘Sarsia’ on three cruises to the Western Approaches of the English Channel and two to the La Chapelle Bank region. In general appearance it closely resembles Dallina septigera (Lovén) with which it appears to have been confused by Fischer & Oehlert (1891).In 1956 it was obtained on 13 June at position 48° 33′ N., 10° 05′ W. at a depth of 570–770 fathoms, four specimens of shell length 17–25 mm were taken together with seven D. septigera.