Stanley Kemp, Sc.D., F.R.S., Secretary of the Marine Biological Association of the United Kingdom and Director of the Plymouth Laboratory, died on 16 May 1945 at the age of 62. His death at the height of his power has come as a most grievous blow to both marine science and zoology in general.

1. The natural history in culture of the species of Nitzschia originally 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 from Nitzschia closterium (Ehr.) W. Smith.

1. Diameter measurements of Rhizosolenia styliformis from the Antarctic, the subtropical Atlantic and Pacific Oceans and from the North Sea and neighbouring waters have made it appear necessary to set up two varieties, oceanica and semispina, in addition to the type of the species R. styliformis. The type as I describe it has been called var. longispina by Hustedt, but elsewhere it has often been figured as the var. oceanica of this paper. Var. semispina is synonymous with the form represented by Karsten as R. semispina Hensen. It differs from R. semispina as drawn by Hensen and its synonym R. hebetata forma semispina Gran, but is thought likely to be linked by intermediates. If this is so R. hebetata may have to be extended to include and suppress R. styliformis, as var. semispina is linked to the type by intermediates. Var. oceanica has no intermediate forms and, if R. hebetata is to be extended, this variety should be established as a separate species.

2. Var. oceanica is absent from the southern North Sea and appears to be an indicator species related to oceanic inflow.

3. Auxospore formation was observed for the type in the southern North Sea in 1935 and biometric observations suggest that a period of 3-4 years elapsed between the production of auxospore generations in that area. Outside the southern North Sea for the type, measurements give no indication of auxospore generations occurring at intervals exceeding a year. While auxospore formation has been seen in var. oceanica from the Shetlands area samples of June 1935 and July 1938, this phenomenon has not been observed for var. semispina.

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.

There is a great demand for algal cultures in studying morphology, cytology, ecology, cellular pathology and physiology, identification of species, and biotic interaction, and also in feeding small animals in culture for various studies. It is hoped that the following note may be of some use to those who want to start making pure cultures of marine phytoplankton organisms.

1. A brief survey is given of the methods for the estimation of mercury by means of dithizone.

2. The precautions necessary in mercury estimations are outlined and the stability of dithizone in chloroform solutions shown to be satisfactory.

3. Data are presented on the rate of extraction of copper, from sea-water solutions, at low pH values with chloroform and carbon tetrachloride solutions of the reagent. Using the former solvent the rate of extraction of copper is shown to be slow, while mercury is rapidly extracted under the same conditions.

4. The use of potassium cobalticyanide in combination with a chloroform solution of dithizone has enabled a method to be developed which eliminates interference of copper in mercury estimations; with the procedure given, mercury in concentrations of 1 to 55µg/l. may be determined in the presence of copper concentrations up to 69 mg./l.

5. Copper may be determined in the same solution subsequent to the mercury estimation by the use of sodium diethyldithiocarbamate, after the solution has been made alkaline with ammonium hydroxide.

The prosobranchiate gastropods are divided into three orders, the Archaeogastropoda, the Mesogastropoda and the Stenoglossa. In the first of these groups the gonad is connected with the right kidney by a duct which is developed from the ovary, and the sex cells escape to the posterior end of the mantle cavity through the right ureter. The eggs are usually shed singly into the sea where fertilization occurs. In the Mesogastropoda and Stenoglossa the right kidney is not developed and the ovarian duct leads to a short and narrow section of the genital duct which is typically ciliated, and may communicate with the pericardium by a gonopericardial duct and passes anteriorly to a long glandular tract running forwards to the mouth of the mantle cavity. This glandular section is incipient in the archaeogastropod Calliostoma zizyphinum. It is probably formed, as Thiele (1935) suggests, by an ectodermal intucking and will be referred to as the pallial oviduct, for it lies anterior to the opening of the original right kidney, and must be derived from the ectoderm of the mantle (Bourne, 1908; Giese, 1915). The short duct which links it with the ovarian duct will be termed the renal oviduct: in Paludina (=Viviparus), in which its development has been investigated (Drummond, 1903), it is formed from the vestige of the right kidney, and even in the highly specialized Stenoglossa it retains the connexion with the pericardium which is characteristic of the right and left kidneys of the archaeogastropods. Similarly, in the male system of the Mesogastropoda and Stenoglossa there can be distinguished a testis duct, which is connected to the posterior end of the mantle cavity by a renal vas deferens, and this in turn is followed by a pallial vas deferens.

The feeding mechanism of the nudibranch Calma glaucoides (Alder & Hancock) has been described by Evans (1922) and that of the crustacean Nebaliopsis typica (Sars) by Cannon (1931) and myself (1943). Calma is seasonally relatively abundant in the coastal waters of parts of Europe where it is found attached to the eggs of certain fishes. It is known to feed exclusively on these eggs and young embryos. Nebaliopsis is a deep pelagic form from the Antarctic Ocean. It has been obtained only rarely and cannot be observed alive and in its natural environment. Two specimens were available for examination. Thus complete certainty about the diet is impossible. The external features and mouth parts were described by Cannon and the structure of these suggested that Nebaliopsis, like other known Nebaliacea, might be a filter feeder. Examination of the morphology of the gut and its contents indicates that this is very improbable. There is no mechanism for the sorting out of particles of different sizes such as is found in other filter feeders. The food passes into a blind sac and there is no apparent means by which the large quantities of indigestible material taken in when particles are filtered from the water indiscriminately might be evacuated. In addition to this negative evidence the food mass found in the large storage chamber of one specimen was completely homogeneous and structureless, its appearance in section suggesting coagulated yolk. It has therefore been suggested that Nebaliopsis feeds on fish eggs found floating in the deeper water layers.

1. Aloidis (Corbula) gibba is a eulamellibranch specialized for life in muddy gravel substrata to depths of up to about 80 fathoms.

2. The shell is asymmetrical, the margin of the smaller, left valve being uncalcified and so fitting within the marginal region of the right valve. A possible manner in which this asymmetry is produced by the differential secretory activities of the two mantle edges is discussed.

3. The marginal periostracum of the left valve has strengthening calcined regions posteriorly, probably to protect the siphons when extruded.

4. The external ligament is reduced and the resilium condensed, possibly permitting some antero-posterior rocking of the shell valves when the adductors contract.

5. The process of burrowing is described; on its completion the animal is anchored by a single byssus thread.

6. The siphons are very short, the tentacles of the siphonal sheath lying on the surface of the substratum. The inhalant siphon is wide and relatively insensitive; it draws in much bottom material. The exhalant siphon is tubular and very sensitive. It is controlled by two paired bands of muscle.

7. The great quantities of pseudo-faeces which accumulate are expelled by periodical contractions of the 'quick' portions of the adductor muscles, the asymmetry of the shell valves causing great reduction in the size of the inhalant chamber. The foot may also assist in clearing the chamber. 8. The large ctenidia create a very powerful current; they are adapted for dealing with large amounts of sediment by means of specialized terminal, guarding and cirrus-like cilia. Control of 'pumping' is primarily by means of the exhalant siphon.

9. The stomach is large in correlation with the great amounts of inorganic material carried in with the food.

Tumtella communis is a highly specialized burrower in gravelly mud. Once buried, it moves little in correlation with its apparently exclusively ciliary feeding habit. An inhalant depression in the mud is made by lateral movements of the foot. There is a unique exhalant siphon constituted by two overlapping folds, and through this water and faecal pellets are expelled without disturbing the surrounding mud.

In the many references to Teredo from Plymouth early workers assumed that the common form was T. navalis L. Orton (1913) refers to this species, but he has recently told me that he did not try to identify the species precisely. It is almost certain that he was dealing with T. norvegica Spengler, which, it is now known, is the common large species in these waters. Harington (1922) ascribes the species with which he worked at Plymouth to T. norvegica, with a query, and no doubt he identified the species correctly. Yonge (1926) states that the Teredo with which he worked from the experimental raft near Plymouth Breakwater were probably all T. norvegica. Later he identified them as that species. Unlike T. navalis it does not carry its young in a brood pouch, but sends its eggs directly into the sea.

Three species have been found in recent years from the Plymouth district, two from the experimental raft moored near the Breakwater and from other fixed wood, and one from driftwood. The two commonly occurring from the raft are (1) T. norvegica and (2) a much smaller species carrying its young in a brood pouch, closely related to, if not identical with, T. navalis. The third species, occurring occasionally in driftwood, is T. megotara Forbes & Hanley. Purchon (1941), who worked at the last species from specimens in a tank at the Plymouth Laboratory, saw no sign of a brood pouch; and in those collected later from Wembury and examined by myself it was found that the eggs, shed directly into the sea, were very numerous.

This paper does not give a detailed description of the backbone of any one of the eight isospondylid species examined. Instead, selected data have been used in a discussion of the broad principles of vertebral variation, as seen in fishes of the order Isospondyli. This was considered to be of greater value than a catalogue of vertebral details for each of a small number of already wellknown species. Even so, sufficient has been said to enable any worker to identify the backbone of any one of the eight species, as well as to obtain a most discriminative description of the backbone of any other species of Isospondyli he may examine. A distinction is drawn between the countable vertebral characters, which are statistics for the precise measurement of vertebral variation, and the 'marker' characters, which provide the means for recognition 'on sight'. It is believed that vertebral characters of both kinds might be profitably employed in the study of different biological populations of the same species. The correlation between vertebral characters and other bodily features, such as keeled scales, position of fins and anus, and contour of body cavity, receives attention, and is related to metamerism. Finally, the occurrence of autogenus vertebral arches and the bifid condition of the neural spines in the isospondylid backbone is shown to be primitive and not restricted to the order.

1. It is suggested that the population of haddock (Gadus aeglefinus L.) on the Porcupine Bank is largely a self-contained stock.

2. This stock had complete immunity from trawling from December 1940, to September 1944.

3. In 1939 and 1940 there was an abundance of small haddock in this stock, due to the good brood of 1938. In 1944, this brood was still very abundant, and was then joined by the good brood of 1942.

4. These two good broods, growing up immune from fishing mortality, caused the Porcupine Bank to carry, in 1944, the densest stock of haddock ever experienced there.

5. The average number of sclerites in the first zone of the scales of these fish is the highest recorded in any region. It is still high in the second zone, but in the later zones falls below that found in the scales of haddock from other regions.

6. The growth rate was faster, in the first four years of life, than even that of Iceland and Faroe haddock, but in the later years it fell behind these, though still superior to the growth rate of the North Sea haddock.

7. The expectation that this greatly increased stock of haddock, due to the war-time cessation of fishing, would show a slowing in its rate of growth, due to intensified competition for the available food, is not supported by the facts.

1. There are three herring fisheries carried on from Milford Haven, namely, a winter drift-net fishery, a spring drift-net fishery, and a trawl fishery in the summer and autumn. These fisheries provide herrings nearly all the year round.

2. There is evidence that the three fisheries are based on the same stock of herrings, and the annual migrations of these herrings, are deduced from statistical data.

3. There is a correlation between the results of the winter drift-net fishery and the following summer and autumn trawl fishery, so that it is possible to make an estimate of the prospects of the important trawled herring fishery some months in advance.

4. There is no evidence that the catches in any one season fluctuate with the moon's phases, but it is found that, in seasons when the moon was full in the last fourteen days of September, the result of the trawl herring fishery has almost always been poor.

There are various short and incomplete accounts of the capture of prey by Sepia scattered 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 of Sepia that 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. Sepia often 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.

A variety of Sabella pavonina Sav. described by Hornell as bicoronata has been found at Plymouth. It is characterized by the unequal development of the two sides of the branchial crown. The characters by which Sabella pavonina, its variety bicoronata and Spirographis spallanzanii may be distinguished are described. It is concluded that the genus Spirographis is not valid and that its species should be referred to the genus Sabella which is redefined.

Subjection to a variety of fluids confirms the presence of two non-living membranes roundv the developing eggs of Homarus. It also reveals that the outer membrane has the restricted permeability of cuticle and the inner membrane the free permeability of chitin.

The inner, chitinous membrane bursts when the egg contents swell; the outer membrane stretches, up to 50 % above its initial diameter, when the internal osmotic pressure rises. It also has considerable elasticity.

These properties of the outer membrane enable it to withstand the pressure to which the developing eggs are subjected and also to stretch during the development of the embryo, hence they have,considerable biological significance.The inner, chitinous membrane, which does not stretch, is probably ruptured and absorbed during development.

By the death of Lord Moyne, assassinated in Cairo on 6 November 1944, the Association has lost a very distinguished member who had contributed generously to improvements at the Plymouth laboratory and had himself made important contributions to Marine Biology. Lord Moyne had been a Governor since 1929; he was President of the Association from 1930 to 1939 and was a Vice-President at the time of his death. During the past year the Association has also suffered by the loss of Mr J. R. Norman of the staff of the British Museum, who had served on a number of occasions as a member of Council.

Four ordinary meetings of Council were held during the year, two in the rooms of the Royal Society in London, one in the Zoological Laboratory at Cambridge and one at Plymouth. At these the average attendance was II. The Association is indebted to the President and Council of the Royal Society and to Prof. Gray for their kindness in providing accommodation for three of the meetings.

The Plymouth Laboratory

During the year considerable progress has been made in the restoration of the laboratory buildings. When it became evident that enemy raids on Plymouth had ended repairs to the asphalt roofing of the buildings were carried out and the lantern light in the library was renovated, while extensive work was undertaken by the laboratory staff. Included in the latter was the replacement of numerous panes of glass in the main laboratory, the reglazing and complete internal redecoration of the library, and repairs to the constant temperature rooms.