Throughout a complete year from September, 1915, to September, 1916, sea-water samples were taken regularly two or three times a week from beyond the Breakwater in the region of the Knap buoy, 2½ miles from Plymouth shore, from the surface and at 5 and 7 fathoms, The object was to supplement the existing records from the tow nets as it is well known that a very large amount of material is lost even from the finest nets, as Lohmann has shown exhaustively (1908). So far the only plankton records from this region have been from the tow nets, and a glance at the tables given at the end of this paper will show directly, if compared with those by Gough (1903–7) and Bygrave (1911), also Cleve (1899 and 1900), the great difference in numbers of the smaller forms, or their entire absence from the tow nettings. Again, no actual numerical records have been given from this region. At the same time as the water samples were taken, tow nettings, coarse, medium and very fine, were also secured, and these were regularly examined for comparison.

[The stages in the development of Calanus finmarchicus described and figured by Miss Lebour in the present paper were taken from culture jars given into my charge by Mr. L. R. Crawshay, when he left the Laboratory to undertake military duties in connection with the war. In one jar at that time the first copepodid stage, from eggs laid in the jar, had just been reached, and the technical details for the successful rearing of the animals had been mastered. The experiments had been conducted with great care, and all possible precautions had been taken to prevent contamination. Subsequently the experiments were repeated up to a certain point by myself and some additional stages obtained to complete the series.

The cultures were made in 2-litre glass beakers, containing “outside” sea-water filtered through a Berkefeld filter. In order to secure an even temperature the beakers stood in the circulating water of the Laboratory tanks, and a pure culture of the diatom Nitzschia closterium was used as food.—E. J. Allen.]

Although much investigation has been made on the food of adult fish the information as to the food of the very young is scattered and fragmentary. It is the purpose of this paper to report on the food of a number of post-larval fish which have been examined fresh from the tow-nettings through the year 1917 from Plymouth Sound within the Breakwater and outside as far as the region of the Panther and Knap Buoys (about 2 miles from the shore) and occasionally from Cawsand Bay. The food of a number of preserved post-larval fish has also been investigated which were taken in the Young Fish Trawl in 1914 and reported on by Dr. Allen (1917).

Sections I and II. Amongst the stock of Gammarus chevreuxi which had been kept under Laboratory conditions for at least two years a small number of animals appeared in which the coloured retinal pigment was absent, whilst the white extra-retinal pigment remained. The experiments described in the present paper have shown that these eyes were of two different kinds.

Eyes of the first kind were derived from a stock which originated in a cross between Black-eyed and Red-eyed animals, and were degenerate and irregular in shape. Four animals of this kind appeared in one brood, and such eyes have since been seen only in direct descendants from these. Eyes of this kind were found to behave as simple Mendelian recessives to eyes showing coloured retinal pigment, whether that pigment was red or black, and they are referred to in this paper as “albino” eyes.

1. Twenty-one thousand, five hundred and fourteen (21,514) amphipods of the species Gammarus chevreuxi Sexton have been examined for eyecolour, 21.302 referred to in this paper, and 212 in other experiments, not included.

2. The normal eye-colour of this species is black, with a superficial reticulation of opaque white pigment.

3. The pigmentation of the eye is very variable within limits. Eyes have been observed either partially or entirely lacking in the coloured pigment of the retinular cells, or with either a partial or entire lack, or else an excess of the opaque white pigment.

4. The red strain appears to have arisen as a “sport” in the second generation of offspring of the first animals captured. No red-eyed animals have yet been found in natural conditions, although many thousands have been brought in from time to time and examined. Those counted for the purpose while the work for this paper was in progress numbered 8697, but this figure does not include the many thousands previously observed. Experiments have been made repeatedly with a view of getting the Red strain again from the Pure Black, but with no success.

The following list includes all the Peridiniales identified in the plankton throughout the year from September, 1915, to September, 1916, from the water samples, details of which will be found in another paper in the same journal (p. 133). Also from the plankton in the tow nets in the same year and a portion of the summer 1915. As is shown in the abovementioned paper, the summer is the time for nearly all the Peridiniales, June being the maximum month. After October very few are seen in the water samples, although in the tow nettings the larger and stronger forms, such as Ceratium and Peridinium, are still present.

It is only within comparatively recent times that it has been proved that the otoliths and scales of certain Teleostean fish can be used for the determination of their age.

Rings of growth, as they are called, are produced on these structures, and it is by counting the number that the age is ascertained, in much the same way as the approximate age of a tree may be determined by counting the annual rings.

Of the many branches of biological enquiry which have occupied the attention of naturalists during the last twenty years the one which has perhaps yielded the most striking results, from a theoretical point of view, has been the study of heredity in plants and animals—the study of the laws according to which the characters of parents are transmitted to their descendants.

In the early summer of 1915 it was' noticed that many medusæ brought in with the tow-nettings contained larval Pycnogonids in the manubrium and at the junction of manubrium and stomach. The medusæ specially noticed to contain them were Obelia sp., Cosmetira pilosella, Turris pileata, Stomotoca dinema and Phialidium hemisphericum. By far the greater number were in Obelia, although many were in Phialidium hemisphericum and Cosmetira pilosella. They were extremely abundant in June, after that became scarcer, and finally disappeared by October. On examination they were seen to be larval stages of Anaphia petiolata (Kröyer), a Pycnogonid common in Plymouth Sound. The older larvæ sometimes were seen to cast their skins, so that the species could be easily recognised, although the fourth pair of walking legs were not fully developed. This is evidently the species described by Dogiel (1913) as Anoplodactylus pygmœus, the life history of which he traces from its first entry into the Obelia hydroid to the older stages when it is ready to leave its host. The form he refers to as Anoplodactylus petiolatus occurring in cysts in Coryne with Phoxichilidium femoratum must be some other species, as his figures prove clearly that it differs from A. pygmœus, and also the colour is totally different (a bright pink, while the present form is a pale yellow). Dogiel believes he has proved that Anoplodactylus petiolatus and A. pygmœus are different species from the difference in their life histories, and it is evident that he is dealing with two different species, but his A. petiolatus cannot be the same as our form, which is certainly identical with his A. pygmœus, and shows that Sars (1891) and Norman (1894) were right in regarding A. pygmœus as the young form of A. petiolatus (Kröyer).

It may perhaps be well to say that by maritime species are meant those Beetles whose habitats are covered by the sea for a considerable time during the flow and ebb of the tide. By sub-maritime species are meant the dwellers at high-tide mark or thereabouts, subjected to occasional wettings by the sea, and the species inhabiting brackish pools and wet places in salt-marshes. The coast species comprise individuals living under stones and rejectamenta, as a rule safe from the reach of high tide, and those peculiar to the roots, leaves and flowers of plants attached to the coast, as well as inhabitants of wooden piles on the shore and the denizens of the ooze of fresh-water trickles on the cliffs—excepting species equally obtainable inland.

…Passing now to the special subject of my address to-night, I will ask your attention in the first place to some general aspects of our Sea Fisheries as a source of national food supply and to the general scientific investigations which have been undertaken in the hope that the yield of the harvest of the sea may be still further increased. In the second place a more detailed account will be attempted of some particular researches bearing upon these matters, which happen to have formed during the past few years the subject of my own special work. If in the course of my remarks you may seem to be asked to follow me in excessive detail into some of the more remote corners of the problems which arise, my excuse must be that, even at the risk of upsetting the balance of the picture as a whole, it is probably possible to speak to more purpose and with a better prospect of stimulating others to fresh efforts, by describing researches with which I have been personally concerned, than by a more general and better proportioned, but necessarily more superficial treatment of the whole subject.

Sagitta has been several times noticed as a host for various parasitic worms, notably a larval nematode and several trematodes. Larval cestodes have also been seen in it. It is exceeding voracious and apparently eats almost any animal food, especially its own species and small Crustacea, so that it is not to be wondered at if it forms a convenient intermediate host for many worms, and as Sagitta itself is an important fish food it naturally follows that the adults of these parasitic worms are usually found in fish as their final hosts. So far, however, the life histories of the larval forms hitherto found have not been determined, so we are pleased to be able to identify two trematodes belonging to well-known species which inhabit Sagitta as intermediate host and fish as the final host.

The larval form (late cercaria stage) of Pharyngora bacillaris (Molin) has been recorded by Nicoll (1910) from Plymouth as occurring free in the coarse-meshed tow-nettings in August. The adult is a common parasite of the mackerel, and the above is the only record of its larval stage.

Whilst examining tow-nettings at Plymouth in 1915 it was found that certain medusæ were at times abundantly infected with a trematode which proved to be the larval form of Pharyngora bacillaris. As it also occurred free, although almost certainly having originally come from the medusæ, it is obviously the form recorded by Nicoll, who expected the host to be a crustacean and unsuccessfully examined copepods in order to find it.

The medusæ found to contain the trematode were Obelia sp., Cosmetira pilosella, and Turris pileata. Cosmetira pilosella was the commonest host in the early summer when Pharyngora was most abundant, but in the later summer Obelia was found to contain it frequently, Cosmetira not occurring at those times in the tow-nettings. Phialidium hemisphericum was also a host in the later summer and autumn. Even in December it still occurred, though very rarely. A ctenophore may also serve as host for this trematode, as it is occasionally found clinging to the inside of the stomach of Pleurobrachia pileus.

The parasite is generally to be found clinging to the manubrium or stomach wall of its host, but sometimes it occurs underneath the umbrella wall, so that it looks as if it were on the top, the wall being so transparent; on further examination, however, it is seen to be underneath.

On May 30th, 1916, a number of large Buccinum undatum were brought in from the trawling grounds ; 40 of these were examined and 34 were found to contain larval Trematodes. Another lot in the spring of 1917 contained about the same percentage of infected Mollusks. Two species of Trematodes were present, both contained in the digestive gland, which was absolutely riddled with them.

Table XLV. is perhaps of interest, as showing the composition of the catch obtained with the young-fish trawl at different times of the year. It has been obtained by combining certain groups of hauls made in 1914 in the offshore waters outside Plymouth, all of them being beyond the 20-fathom line. As far as the conditions are concerned therefore the different groups are fairly comparable. The figure given for each species is the average number of specimens per haul for the group. It will be seen that after June the number of species present as well as the average number per haul are both very much reduced.

At a time like the present, when the Empire we have inherited stands facing a crisis of its fate, when indeed the whole structure of civilization as we know it has seemed to sway, when that which generations of earnest thinkers have dreamt of as the progress of the race recoils before the forces it has itself unchained, it is difficult to restrain a feeling of incongruity in discussing any subject that has no obvious bearing on the greater problems of the hour. But I am convinced that we are following the right course in carrying on, with such help as remains available, the work of this Association, whose object is the advancement of Science, Literature and Art. In the short, swift cataracts of war, no less than in the gentler, steadier flow of peace, these matters of the mind have still their power.

The amount of phosphoric acid in sea-water off Plymouth was at a maximum of 0.06 mg. per litre of P2O5 at the end of December, 1915, after which it fell irregularly to a minimum of less than 0.01 mg., which extended from the last week of April to the latter part of May; it then increased again and in January, 1917, reached the same value as the average for the first part of the month in the previous year.

This seasonal variation is probably to be attributed to the removal of the phosphates from solution, at first by the fixed algæ, and later in the spring by the diatoms and for a short time by Phcœcyslis. There is also present in sea-water taken near Plymouth another soluble compound of phosphorus which can be converted into phosphoric acid by oxidising agents.

Cirratulus tentaculatus is found inhabiting the wet, sandy, somewhat foul mud of the Aberystwyth shore, chiefly in the Laminarian zone, although it also occurs in rock pools higher up the shore in which there is sufficient depth of sand containing the necessary organic matter. The presence of the worm in its natural habitat is indicated by a group of delicate, elongate, rosy or yellow coloured filaments of tentacular appearance which protrude from the sand into the pools left by the receding tide. These filaments nearly always display a certain amount of movement, either waving gently from side to side or curling slightly from the tips. The amount of motion and also the colour of the filaments will depend on the degree of freshness of the water in the pool, and this, of course, will, in its turn, be related to the state of the tide.

Specimens are not easy to collect owing to the marked propensity the animal exhibits for lying with its body beneath stones or pieces of rock embedded in the mud. In rock pools or crevices where there is but little depth of sand and the animal lies with its body more or less parallel to the surface collection is almost impossible. This response to stimuli of contact and pressure, or, as M. Georges Bohn has it, this “thygmotactism,” is very marked, and, in the aquarium, when specimens are placed in a vessel containing sand and a few stones, the animals will roam about till some portion, at any rate, of their bodies is undergoing pressure from those stones.