An examination of Hodge's original slides of marine Acari shows that three alterations in synonymy are called for: (i) Simognathus sculptus (Brady, 1875) to become a synonym of S. minutus (Hodge, 1863); (ii) Copidognathus oculatus Hodge, 1860 to become C. oculatus Lohmann, 1889; (iii) C. glyptoderma Trouessart to become a synonym of C. granulatus (Hodge, 1863). Observations were also made on the permanence of Dean's Medium as a mountant for small arachnids and some quotations and observations on the value of certain diagnostic characteristics of the genus Copidognathus are made.

As known from ancient times, Electric Rays (Torpedo) have the power of giving severe numbing shocks, and it has repeatedly been stated that this power, which is electrical, is used both as a means of protection and for paralysing prey. That the shock is used in the capture of prey seems never to have been definitely proved. Indeed Roule (1935, p. 161) expresses the opinion that the electric shock is not used for securing food and even doubts that it is normally and effectively used as a means of defence. There appears to be no detailed account of the manner in which Torpedo feeds, but the ninth edition (1925) of the Guide to the Aquarium of the Zoological Station at Naples mentions (p. 106) that the Electric Ray rises from the mud to throw itself against approaching mullet (Mugil), and that the mullet, overcome by fright and electric shock, fall to the ground to be eaten. This very short and incomplete account was not seen until after the following paragraphs had been written.

Both Torpedo nobiliana Bonaparte and T. torpedo L. occur from time to time off Plymouth, the former being by far the commoner, and both have been kept in our aquarium tanks. They are sluggish fishes, spending most of the time lying still on the bottom, occasionally swimming for short spells. They swim by sculling with the tail, which has a large caudal and two dorsal fins. This mode of swimming differs strikingly from that of normal rays, which undulate the pectoral fins and trail their tails' it resembles the swimming movements of Rhina squatina (L.), another fish with a sluggish disposition and, as noted below, some other resemblances to Torpedo.

Munro Fox (1926, Addendum, p. 219) described a method of preparation of chlorocruoroporphyrin from the blood of the marine polychaete worm Spirographis. This was based upon the very troublesome method of Nencki & Zaleski (1900), which is time-consuming and wasteful. Furthermore, Spirographis is not easily obtainable in this country. Lemberg & Parker (1952) started with protoporphyrin, and by careful oxidation with potassium permanganate in acetone obtained a solution which gaVe mixed crystals of chlorocruoroporphyrin and diformyldeuteroporphyrin esters. Purification was by fractional chromatography. The procedure to be described here is simple and rapid, and could easily be carried out in one day by a biologist requiring a small sample of the porphyrin. The two methods mentioned above would not come into this category.

This work was done at the Plymouth Laboratory, and I am very grateful to Mr T. R. Tozer of that laboratory for so kindly obtaining the animals for me and extracting the blood.

The polychaete worms Myxicola infundibulum, Sabella pavonina and Branchiomma vesiculosum are all readily obtained from the muddy shores of the Salcombe estuary, especially on the Salstone. Blood was taken directly from the vessels of about 100 assorted worms by syringe, and squirted as it was removed from the worms into a mixture of peroxide-free ether (3 parts) and ‘Analar’ glacial acetic acid (1 part). After all the blood had been added, the mixture was well shaken and allowed to stand in the ice-chest for 30 min. The acetic acid was then washed out with distilled water, the first few washings containing a little sodium acetate to avoid washing out of the pigment, and the remaining solution of chlorocruorohaematin dried roughly by filtering through ether-soaked paper into a distilling flask and evaporated to dryness. 100 ml. of a 50% solution of hydrazine hydrate in glacial acetic acid were then added, and the mixture heated on a water-bath at 90° C. for 10 min.

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.

If Arion hortensis be fed on a diet which contains 90Sr, autoradiographs show that the isotope istaken up by the digestive and lime cells of the digestive gland. From the former it passes to th haemocoel; in the lime cells it is concentrated around the calcium spherules. Some of the tracer enters the body through the wall of the intestine. Calcium stores which surround blood vessels and calcium cells in the mantle also concentrate the tracer.

In Aplysia.punctata 90Sr from the surrounding water passes through the surface of the body, and especially the gill; in Acanthodoris pilosa ions which enter the tissues from the sea water accumulate around the numerous calcium concretions in the mantle. These marine molluscs obtain cations directly from the water as well as by way of the food.

There is a slow uptake of strontium ions by the ctenidia of Mytilus edulis, though, even in filtered sea water, the gut is the more important area for their ingress to the body. It is possible that they enter with the mucous feedingsheets. They pass readily into the cells of the digestive gland. Some of the isotope taken in with the food is absorbed by the wall of the intestine; this also occurs in Patella vulgata, in which the intestine provides a much larger area, and in Lepidochitona cinereus.

Mytilus placed in filtered sea water which is activated with 90Sr, so increasing the strontium content by 007%, show the tracer localized for excretion within 10 hr. Ions are aggregated in the pericardial glands, not in the kidney.

A porphyrin pigment found in Asterias rubens has been re-examined and found to be protoporphyrin, and not haematoporphyrin as originally reported by MacMunn. The pigment was identified by spectroscopic and spectrophotometric observations as well as by chemical tests and the use of paper partition and column chromatography. The protoporphyrin is absent from the gut, gonads and digestive caeca, and is present only in' the leathery integument.

The porphyrin occurs in the integument as free protoporphyrin; a yield of 33-6 mg. of red crystalline protoporphyrin dimethyl ester was obtained from a sample of 5485 g. of Asterias integument.

The relative amounts of protoporphyrin in different coloured specimens of A. rubens were determined by a fluorimetric method. With four well-defined colour types the amount of porphyrin per gram of integument was found to decrease rapidly in the series: violet-brown, dark brown, red and pale.

Neither protoporphyrin nor a porphyrinogen was found in the soft parts of Chlamys opercularis or Mytilus edulis, the main food animals of Asterias in the Plymouth area. The exact source of the integumentary porphyrin in this starfish is therefore uncertain, ,but it is suggested that it may be derived from the chlorophyll pigments found in the digestive caeca.

The porphyrin does not contribute materially to the colour pattern of the animals, most of whose colour is carotenoid, and it is most likely that it is a by-product of excretion formed from chlorophyll.

Regeneration of the siphons of normal specimens Ciona intestinalis has been found to be completed, in every particular other than that of length, in 4 days.

Removal of the neuroglandular complex retards the regeneration rate.

With the exception of the epidermis and of the basic tunic, the new structures differentiate from haemoblasts.

A tentative synthesis has been made of the information available upon asexual reproduction and regeneration in the Ascidiaceae.

An apparatus in which it is possible to observe the horizontal migrations of zooplankton in gradients of phytoplankton is described, and an account given of its use in experiments involving various organisms. A preliminary search for toxic organisms is also described.

The experiments comprise a demonstration of a migration by various animals into concentrations ofthe diatoms Skeletonema, Thalassiosira, Biddulphia, Nitzschia and various mixed cultures and the flagellates Chlamydomonas, Peridinium, Dicrateria, K, and Oxyrrhis. Cultures of Rhodomonas and Gymnodinium II are found to produce the opposite effect, and no reaction towards Lauderia, Coscinodiscus, Eucampia, Syracosphaera and Exuviaella could be shown. Results with bacteria cultures andvarious inorganic gradients are also discussed.

A second apparatus in which it is possible to observe the vertical migrations of zooplankton in the presence and absence of phytoplankton is also described, and an account given of experiments in it involving various organisms.

The experiments comprise a demonstration that greater numbers of animals swim up in the presence of mixed phytoplankton cultures, Coscinodiscus, Skeletonema, Ditylum, Chlamydomonas, Gymnodinium I and II and Oxyrrhis than in unenriched water. Flagellate One has no effect and Chlorella possibly depresses the number swimming up.

Under-water observations on the swimming movements of some of the animals used are described. The possible application of the observations towards resolving the problem of the inverse distribution of phytoplankton and zooplankton in the sea is discussed, and the hypothesis is proposed that this may be accounted for by a combination of migration and grazing. It is considered that plankton animals must migrate both horizontally and vertically into patches of phytoplankton and, when present in sufficient numbers, graze these down very quickly.

During 1946 and 1947, regular samples of Mytilus edulis from a number of localities ontheBritish coasts, including Conway, Brancaster and Liverpool, were examined for gonad conditionand spawning. For each sample, the mean stage of gonad development was computed. The criteria employed in distinguishing the stages of gonad development are described.

Ripening of the gonads takes place within a few weeks of the onset of spawning, in general commencing when the sea temperature has risen above 7–0° C. There appears to be no correlation between nutritional condition and ripening of the gonads, or subsequent spawning.

In all localities and in each year in which observations were made spawning occurred in late spring (mid-April to the end of May) and in most areas lasted for a short period only (2–4 weeks). At Brixham, in 1949 and 1950, the duration of the spawning period was longer (4-6 weeks). In most cases, 70–80% of the mature population spawned during the first 7–10 days of the breeding period. No evidence of periodic spawning was obtained.

In all cases, spawning commenced in a period during which the mean temperature to which the mussels were exposed was rising from c. 9–5° C. to 11–12–5° C. In most cases, the onset of spawning was coincident with a period of spring tides, and of predominantly bright sunny weather. The initial rate of spawning appears to be directly related to the rate of increase in mean temperature to which the mussels are exposed.

After spawning, mussels enter into a ‘neuter’ or ‘resting spent’ stage in which all traces of sexuality are lost.

An account is given of the general structure of the body skeleton of the spatangid larva. A considerable change occurs in the skeleton as the larva increases in size, some parts being absorbed and new parts appearing. Of particular interest is the replacement of the anterior transverse rod by the ventral horizontal rod.

The skeletons of larvae, young stages to late stages, of Echinocardium cordatum, E. flavescens, Spatangus purpureus and Brissopsis lyrifera are described. The larvae of Echinocardium and Spatangus are, in essentials, very similar; that of Brissopsis differs greatly from them. A striking difference is that in Brissopsis the ventral horizontal rod arises from the postoral arm and anterior to the anterior transverse rod, in the other two genera it arises from the body rod posterior to the anterior transverse rod.

The replacement of the anterior transverse rod by a ventral horizontal rod is probably normal in clypeastroid larvae also.

A method of demonstrating cellulose utilization in biological systems by measurement of the turbidity of a cellulose suspension in a photo-electric absorptiometer is described. The crystalline styles of Ostrea edulis and Mytilus edulis appear to contain a cellulolytic factor as yet uncharacterized.

This preliminary list of some of the classes of the algae has been prepared, mainly for the use of British phycologists, to form a basis on which to work for the eventual compilation of a complete check and locality list of all species of British marine algae. The compiler would be grateful for all additions and corrections to this list, and for records of marine species from the algal classes not included in the present list.

The classes of algae treated in this list are the Chlorophyceae (53 gen., 156 spp.), Xanthophyceae (7 gen., 15 spp.), Chrysophyceae (15 gen., 22 spp.), Phaeophyceae (96 gen., 199 spp.), Rhodophyceae (126 gen., 324 spp.), and Cyanophyceae (39 gen., 125 spp.). The genera are listed alphabetically under the family and the species alphabetically under the genus. If a name has been changed from that given in Newton (1931), the name in Newton is added, in brackets, below. Names preceded by a question mark appear to need revision for nomenclatural or taxonomic reasons. Most of the so-called varieties listed are very probably merely habitat forms of the species, but further investigation is needed before new combinations are made for them. Notes are given at the end of each class, the number in brackets following a name in the list refers to these notes.

The compiler is grateful to Mr R. Ross and Miss Linda Newton, of the British Museum, and to Miss C. I. Dickinson, of the Herbarium, Kew, for their help over a number of problems.

Patron

The Council has pleasure in reporting that His Royal Highness The Duke of Edinburgh, K.G., has graciously consented to become Patron of the Marine Biological Association of the United Kingdom.

The Council and Officers

Four meetings of the Council have been held during the year, three in the rooms of the Royal Society and one at Plymouth. At these the average attendance was seventeen. The Association is indebted ‘to the Council of the Royal Society for the use’of its rooms.

The Council has to record with regret the deaths of two Vice-Presidents, Viscount Astor and Dr W. T. Calman, C.B., F.R.S.; of Dr Th. Mortensen, an Honorary Member of the Association; and of Prof. J. H. Orton, F.R.S., sometime member of Council and for many years a member of the Staff of the Plymouth laboratory.

Thé Plymouth Laboratory

Following the completion last year of the building of the laboratory for research with radioactive substances, the opportunity has been taken of paving the area between this laboratory and the main building with concrete.

The facilities of the main workshop have been improved by the purchase of a milling machine.

The Council is grateful to the Development Commissioners for the supply of a new Morris 10 cwt. truck.

The Aquarium

Throughout the summer months the aquarium was crowded with visitors, and their appreciation and interest is reflected in the sale of large numbers of the aquarium guide book. Tanks have been stocked to capacity, perhaps the most notable exhibits being the wreck-fish {Polyprion americanus), mentioned in last year's report and now in fine condition, and about twenty boar-fish {Capros aper), which make an especially colourful display.