Gametogenesis has been studied in four cirratulid polychaetes: Caulleriella caput-esocis, Tharyx marioni, Cirriformia tentaculata and Cirratulus cirratus.

In all four species, sperm development follows a similar course of events, with the sperm cells being grouped in spheres and then platelets before developing tails to give rosettes which finally disintegrate to release the active spermatozoa. Except in Cirratulus, there is a well-defined annual cycle in the development of sperm.

Oogenesis in Caulleriella and Cirriformia is similar in that the growth curve of the oocytes is roughly sigmoid. In Tharyx the release of the oocytes to the coelom is delayed and discrete ovaries are formed, only the later stages of oocyte growth taking place within the coelom. In contrast to the above three species, oogenesis in Cirratulus does not show an annual cycle.

Maturation of the oocytes within the coelom prior to shedding has been established in Tharyx, Cirratulus and Cirriformia. In the former two species meiosis proceeds as far as the metaphase I stage and in the latter to the anaphase I stage, before the oocytes are released. Fertilizations were achieved only with oocytes which had matured in all three species. In the fourth species, Caulleriella, no fertile oocytes were discovered.

The diameters of the mature oocytes and the main spawning seasons of the four species at Plymouth are as follows: Caulleriella, about 110 μ (August to October); Tharyx, 200– 220 μ (late October to early November); Cirriformia, about 117 μ (late June to early July); Cirratulus, 135–150 μ (throughout the year).

The north-eastern Atlantic gobiid genus Lebetus Winther, 1877, was formerly believed to contain two species, Lebetus scorpioides (Collett, 1874) and L. orca (Collett, 1874). These have been subsequently shown to represent females (and immature fish) and males respectively of a single, sexually dimorphic species whose valid name is L. scorpioides. The discovery of two forms of Lebetus postlarvae, differing in meristic characters, fin growth, and pigmentation, is shown not to affect this conclusion but to suggest provisional recognition of another species, L. guilleti (Le Danois, 1913), with fewer anal fin-rays (A I/5–6) and vertebrae (25–26) than L. scorpioides (A I/7–8; vertebrae 27-29). A key and limited synonymy for the species is provided. As a possible alternative view it is suggested that relatively high summer sea-temperatures during early development of L. scorpioides in certain areas may produce the lower meristic features of L. guilleti.

High- and low-shore populations of Bathyporeia pilosa LindstrÖm, kept in the laboratory under natural day-night illumination and constant dark conditions, show distinct swimming rhythms of tidal frequency (12–4 h) with activity maxima on the early ebb tide. A diurnal component is evident, activity during thenight being greater than during the day. The tidal rhythm deteriorates under laboratory conditions, but swimming activity recurs after a semi-lunar period. Under natural illumination, both populations show a night tide swimming rhythm of semi-lunar frequency, activity occurring mainly over the 'falling' spring tides. Plankton sampling on night tides over the area of the beach occupied by high-shore B. pilosa shows that the animals emerge and swim on ebb tides which are in phase with darkness. The importance of exogenous factors such as wave action, pressure, temperature and light is discussed. Ecological implications and the possible function of the swimming rhythm are considered.

Using 14C as a tracer in experiments of 2–3 h duration it has been demonstrated, both with individual species in culture and natural populations, that marine phytoplankton from tropical inshore waters releases products of photosynthesis insoluble extracellular form. The relative extent of this excretion varied between 1% and 20% of the total carbon fixed but on any particular occasion the amount of extracellular products was approximately proportional to the amount ofphotosynthesis which had taken place. An inverse relation-ship between relative extent of excretion and phytoplankton abundance as measured by chlorophyllα concentration was found, in agreement with the results of previous workers. The relative extent of excretion did not appear to be greatly different in brackish water of 12–3% salinity from that in ordinary sea water.

Information on the population structure and breeding of the following species is presented: Siriella armata (Milne-Edwards), 5. clausii G. O. Sars, S.jaltensis (Czerniavsky),Gastrosaccus spinifer (Goës), Anchialina agilis (G. O. Sars),Psendomma affine G. O. Sars and Hemimysis latnornae (Couch). There is no previously published information on the biology of these species in British waters except notes on 5. armata and A. agilis. Notes on the occurrence of the following species on the west coast of Scotland are also given: Siriella norvegica G. O. Sars, Gastrosaccus sanctus (van Beneden), G. normani G. O. Sars, Leptomysis mediterranea G. O. Sars, Mesopodopsis slabberi (van Beneden), Heteromysis formosa S. I. Smith and Acanthomysis longicornis (Milne-Edwards).

The seasonal maxima of occurrence of 23 species of mysids are examined; the numbers caught of a further four species were too small to draw any conclusions from. The evidence suggests that all species, except possibly two, aggregate; not enough information is available on Acanthomysis longicornis and Heteromysis fortnosa. The types of aggregations formed, whether population swarms or breeding aggregations, are unknown in 10 species. There is evidence of shoal and/or swarmformation in 12 species and of breeding aggregations in 7 species. All species known to form swarms live in shallow water; Leptomysis gracilis is the only species living in deep water that shows evidence of swarm formation. All other deep-water species aggregate, some for the purposes of breeding. Negative phototropism of individuals is suggested as a mechanism initiating aggregation of species in the bottom of deep-water basins. Reaction of one individual to another individual or groupof individuals (social behaviour) is considered necessary to intensify the initial degrees of aggregation and to maintain the integrity of shoals or breeding aggregations once formed. Parallels are drawn between aggregations of mysids and those of euphausiids.

Mytilus edulis L. is shown to acclimate to high and low temperature under laboratory conditions. The warm and cold acclimation of oxygen consumption, filtration rate and assimilation efficiency are described for groups of animals maintained at three food-cell concentrations. Complete acclimation (Precht's type 2) of oxygen consumption and filtration rate occur within 14 days. There is no change in assimilation efficiency within the 28-day experimental period. The results are integrated and discussed in the context of a simple energy budget. In terms of the energy budget there exists a marked contrast between warm and cold acclimation. An “index of energy balance” is proposed in order to assess the state of the energy balance. When animals are fed above the maintenance requirement the energy budget remains in an equilibrium state during cold acclimation, whereas the acclimation to a warm temperature regime disrupts the balance and represents a physiological stress. During warm acclimation, prior to the re-establishment of an energy equilibrium the blood sugar level increases, suggesting that the animal is required to mobilize and utilize its energy reserves.

The concentration of copper in Nereis diversicolor O. F. Miiller is roughly related to the total concentration in the sediment and particularly high concentrations are found where mining pollution occurs. In contrast, the concentration ofzinc in Nereis remains remarkably constant despite wide variations in the environment and appears to be accurately regulated.

The epithelial receptors of Nassarius are primary sense cells. The sensory endings are abundant on the tentacle tips, anterior border of the foot and ventral external surface of the siphon tip. Densities are a small multiple of 1032 endings/mm2.

Type 1 ciliated endings are of ubiquitous occurrence. The ultrastructure of type 1 endings is uniform, though the static and motile bundles of sensory cilia may be distinguished by the random or uniform orientation of the ciliary subfibrils and basal feet. Ciliated receptors probably include both chemo- and mechanoreceptors.

A distinct ultrastructural type of sensory ending (type 2), confined to the siphon tip, consists of a small pit in the peripheral dendrite close to the epithelialsurface. The pit contains whorled microvilli and a few cilia. It may be photoreceptive.

A small amount of convergence of sensory information may occur in peripheral nerve.

Determinations have been made of paniculate iron in samples collected from Southampton Water over a period of 2 years. Concentrations of 106–1046 ug/l. were found. Total amounts of paniculate matter ranged from 1·3 to 48·6 mg/1., of which iron constituted 0–5–14%. Amounts of paniculate matter and paniculate iron showed a highly significant correlation. For one station where wind-speed data were available there was a highly significant correlation between the amount of particulate matter and the mean daily wind speed for the 4 days prior to sampling. No clearly defined seasonal variation in the amounts of particulate matter or particulate iron was found. The concentration of particulate iron in the estuary appeared to be dominantly controlled by meteorological and hydrological factors.

The distribution of the visual pigments within the retina of the rudd, Scardinius erythrophthalmus, and dragonet, Callionymus lyra L., was studied by measuring the spectral absorbance of small areas of intact isolated retinas.

The rudd retina contains two visual pigments, VP 5O71 and VP5352. There is a progressive change in the relative proportion of these two pigments in the dorso-ventral plane, and there are no sharply defined zones each with a different pigment mixture. The proportion of the A1-based pigment (VP 5071) is greater in the dorsal part of the retina.

The maximal optical density of the pigment in the dorsal retina of the rudd was greater (about o·6) than it was in the ventral retina (about 0·3). The difference in the amount of light absorbed, however, is small compared to the intensity difference between the up-welling and downwelling light of the environment. When the relative proportion of the A1- and A2-based pigments was changed by altering the lighting conditions under which the animals were kept there was little or no change in the maximal optical density of the pigment.

In the dragonet the retina shows a clear division into a ventral pink zone (maximal optical density about 0·5) and a dorsal zone that is much paler (maximal optical density about 0·2). The relative spectral absorbance of the two regions is similar, although one is said to be a pure cone region, and the other to be dominated by rods.

The spectral absorbance curves for the intact retinas agreed well with results obtained with pigment extracts.

The amino acid composition has been investigated in two euphausiids, Euphausia superba Dana and Meganyctiphanes norvegica (M. Sars), and one mysid, Neomysis integer Leach. Protein-bound amino acids show a very considerable degree of similarity: glutamic acid, aspartic acid, lysine, leucine and arginine are predominant in all three crustaceans, and occur in that order of importance. Together they amount to ~ 50% of the total protein hydrolysates. Concentrations of free amino acids show greater differences between the zooplankton species, but taurine, glycine and arginine are very important in all three. Lysine and ornithine occur in fair quantities in both euphausiids, and proline and alanine are moderately important in Euphausia superba and Neomysis integer.

Observations on the fine structure of two clones of zoids derived from Phaeocystis pouchetii s.l. are presented, with special reference to the scales, pyrenoids and haptonema, in which both clones agree. An unexplained difference between them in the form of a threadlike deposit external to the scales in one clone only is described in a preliminary way. The most remarkable feature encountered is the presence of some unexplained bulbous inclusions distorting the tip of the haptonema but perhaps also present in a less extreme form in other types recently examined alive. The interpretation of these findings is discussed.

Assimilation efficiency (percentage of nutrients absorbed) from diets compounded from dry food meals was investigated using the prawns Palaemon serratus Pennant and Pandalus platyceros Brandt. An indirect ratio method using chromic oxide (Cr2O3) as an inert reference material in the diet was employed, but the method was complicated by the prawns' habit of regurgitating part of the indigestible food remains after a meal. Thus quantitative collection of both faeces and the regurgitated, unassimilated food fraction was necessary.

The accumulation of radionuclides by I-group plaice, Pleuronectes platessa L., in the vicinity of the pipe-line of the UKAEA plant at Windscale, Irish Sea, has been studied over a 7–month period. The principal isotope found in the flesh was 137Cs, although 144Ce, 106Ru, and 95Zr/95Nb were also present in the gut contents. The 137Cs flesh levels were examined in conjunction with the fluctuations of this nuclide in sea water, sediment and the gut contents. Of the three major dietary components found throughout the sampling period the calculated intake of 137Cs from food appeared to fluctuate most closely with the Nephtys fraction of the diet, despite its relatively low 137Cs content.

The anatomy of the teleost lymph system is considered in relation to the observed flow of lymph. The plaice Pleuronectes platessa L. was studied.

The vessels described by anatomists as longitudinal ventral, dorsal and lateral lymph ducts do not pass lymph to the head but act as collecting sinuses; the lymph flows from these sinuses to the neural lymph duct via the interspinal ducts.

At the junction of each interspinal duct and the neural lymph duct there is a simple valve. Lymph drains through this system as a result of a negative pressure developed in the neural canal by the respiratory movements of the gill apparatus.

The rigid nature of the neural lymph duct and the valves where the interspinal ducts join it allow the negative pressure to develop from a negative positive gill generated pres-sure cycle in the cephalic lymph sinuses. Valves Unking cephalic lymph sinuses aid the return of lymph to the duct of Cuvier using the same pressure cycles.

The drainage system is different in the salmonidae where the neural lymph duct is degenerate and the network of peripheral ducts serve as lymph return ducts. This can probably be explained by the occurrence of higher circulation pressures in the salmonidae.

Lymph from the neural lymph duct is a clear fluid having a composition similar to that of blood plasma. Like blood, lymph clots, and contains normal blood levels of mobile leucocytes and thrombocytes and lymph reflects blood levels of lactate. Lymph contains nearly no erythrocytes and the protein concentration of neural duct lymph is 80–4% that of blood plasma.

Mesopeiagic fish without swim bladders, found in depths from 100 to 1000 m, have soft bodies with a very high water content (88–95%) low haematocrits (5–9%), smallhearts, a low proportion of red muscle, and large lymph ducts. Species possessing swim bladders have a lower water content (70–83%), higher haematocrits (14–35%), larger hearts, more prevalentred muscle and smaller lymph ducts. Some active surface species have still less water (64–74%) and higher haematocrits (48–57%).

The soft watery fish appear to use skeletal reduction and high water content asa buoyancy mechanism but there is no evidence, judging from analyses of freezing-point depression of the plasma and muscle fluid, that they maintain an extra low ionic content to assist buoyancy. Although oxygen is probably adequate in the deep water, there may be some constraint on activity because the oxygen-carrying capacity ofthe blood is low and oxygen may be limited at the tissues. This is partly compensated for by the high proportion of anaerobic white muscle and the large lymph system. These watery fish appear to be best adapted to short bursts of activity. Nevertheless they do make diel vertical migrations which may cause them to reach the limits of their aerobic metabolic systems.

The mesopeiagic species with swim bladders are much more similar in their circulatory characteristics to inshore fish. They also make quite substantial vertical migrations with the concomitant problem of adjusting buoyancy by varying the pressure within the swim bladder. Metabolically this is unlikely to be unduly difficult.

Prof. Jerzy Stanislaw Alexandrowicz, who died at Plymouth on 28 October 1970, was one of the most distinguished histologists of the nervous system, whose series of memoirs upon invertebrate peripheral nervous systems stimulated much physiological and histo-logical research. He was born at Stoczki, in Poland, on 2 August 1886, and after matriculating in Warsaw studied medicine and natural science at the universities of Warsaw, Zurich, Munich, Heidelberg, Paris and Jena. He took his Ph.D. at Zurich under Lang, and his M.D. at Jena, under Biedermann, serving for a short period as a surgeon in the Military hospital at Belgrade, before being appointed to the department of descriptive anatomy at Wilno. He remained here during the war, and in 1918 served with the field hospitals coping with epidemic diseases brought to Poland from the East. He himself survived an attack of typhus. In 1919 he was appointed to organize and direct the department of descriptive anatomy at Wilno, and the next year rejoined the army to serve as the chief medical officer of a cavalry regiment in the fighting against Russia.

In 1920 he returned to Wilno, as head of the department of histology, and remained there until 1929, when he moved to Lwow, again as director of the department of histology, in the Academy of Veterinary medicine. In 1933 he became Pro-Rector of the Academy, and in 1936 Reaor, finally leaving the university in 1937 to head the scientific and university department of the Ministry of Education. He quickly became Under-secretary of State for Education, and in 1938 relinquished this post to spend six months at the Stazione Zoologica, Naples, where he had previously worked on three occasions.