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Forty years ago a suggestion was made (Bunge)1 that the sodium chloride in the human tissues might be a relic, an inherited feature of some aquatic marine ancestor. The same idea was expressed in certain papers by Quinton,2 who stated that so far as salinity is concerned the blood of most animals is an altered sea water. In 1903,3 Macallum, then unaware of the suggestions of Bunge and Quinton, advanced the theory “that the blood plasma of vertebrates and invertebrates with a closed circulatory system is, in its inorganic salts, but a reproduction of the sea water of the remote geological period in which the prototypic representative of such animal forms first made their appearance”. He regarded the differences between the blood salinity of the higher vertebrates and the present-day ocean as due to changes in the composition of the sea water since palaeozoic or mesozoic times. Macallum followed up his first statement by more detailed papers, and made some valuable analyses of blood to support his thesis. He is now generally credited with being the originator of this interesting conception. In 1912 I discussed the matter4 from the point of view of certain experiments and observations on marine and fresh-water invertebrates, and came to the conclusion that whilst one might accept the well-regulated saline composition of the blood of teleost fishes, amphibia, and the higher groups as being to a certain extent an heirloom of an ocean environment, there was no reason whatever to believe that the favoured salinity associated with independence represented the composition of any particular primeval ocean. At that time I stated that the investigations of osmotic regulation did not preclude the idea that the early vertebrates with an independence in blood salinity had evolved in fresh water.

This paper reports the effects of sodium chloride on the in vitro activity of malate dehydrogenase and on the specific activity of malate dehydrogenase isolated from various halophytes and glycophytes grown under saline and non-saline conditions. The influence of substrate salinity on respiration and dark CO2 fixation was also studied. The species used were the halophytesAster tripolium, Atriplex spongiosa, Mesembryanthemum crystallinum, Plantago maritima, Salicornia brachystachya, andSpergularia salina, and the glycophytesAster amellus, Plantago major, andSpergularia rubra.When added to the test solutions, sodium chloride stimulates the activity of malate dehydrogenase. Further addition of sodium chloride results in rapid decline of activity at salt concentrations which vary with the species. Malate dehydrogenase isolated from both glycophytes and halophytes do not show any significant difference in their response to sodium chloride, indicating salt tolerance. Enzyme isolated from halophytes grown under saline conditions is as sensitive to sodium chloride as enzymes isolated from the same plants grown in the absence of additional NaCl. A double reciprocal plot shows a competitive interaction between sodium chloride and oxaloacetate. The addition of sucrose during the in-vitro assay of malate dehydrogenase results in a stronger inhibition than that caused by isosmotic NaCl solutions.Enzymes extracted from seedlings of halophytes and glycophytes grown at various levels of sodium chloride showed important changes in specific activity of malate dehydrogenase (tested without additional sodium chloride in an in-vitro assay). In glycophytes, specific activity decreases with increasing substrate salinity, whereas in halophytes specific activity first increases, to a symptote and finally decreases. A double reciprocal plot shows a non-competitive interaction between sodium chloride and oxaloacetate indicating that the ratio of malate dehydrogenase to total extractable protein is altered by sodium chloride. The respiration of these seedlings runs parallels the specific activity of the malate dehydrogenase whereas CO2 dark fixation declines with increasing substrate salinity.The results are discussed with respect to compensatory reactions rather than compartmentalisation due to the addition of sodium chloride.

The carnivorous marine mite Halacarus basteri was reared on blotting paper in artificial sea water of different salinities. The mites find their food by aid of chemically working sense organs which are situated on the tarsi of the first pair of the legs and perhaps at the top of the pedipalpi. All stages of development straddle with their legs when in open water. Thus the legs become gliding filaments which reduce the sinking speed. Development from egg to the propagating mite takes one year. Sperm transmission is carried out indirectly by spermatophores (Fig. 2).In their normal range of life (salinity from 8 to 25‰) the mites behave poikilosmotic and hyperosmotic. Between 25 and 45‰ they show a hypertonic-hypotonic regulation (Fig. 3). In extreme salinities the mites swell or shrink; they recover in normal salinity (Fig. 4). The mites stand extremely low temperature without damage (Fig. 5).

Two marine and 14 clinical isolates ofA. boydii and its byssoid phase,M. apiospermum, were compared with respect to their saline tolerance, morphological development, and sporulation on various commercial and compounded media. Isolates from sea-water and human infections were morphologically alike, and possessed similar saline tolerance. Most strains had salinity optima near 9‰, about the salinity of blood. Only marine isolates fruited well on Sabouraud's dextrose agar and other routine mycological media. On a medium containing wood and sea-water, and few soluble organics, 12 strains formed mature ascocarps or synnemata, or both. Low nutrient level media containing wood or cellulosic paper, with or without sea-water, were recommended for the propagation and conservation of sporulating cultures of many saprobic Ascomycetes and synnematous Fungi Imperfecti.

A previous paper (Part I)4 has shown that when vegetation and land slope are favourable to the capture of aerosol, the salinity of rainfall provides no measure of rate of acquisition of cyclic salt by a given land area.

1. Our present information on non-genetic adaptation of intact aquatic organisms to temperature and salinity does not yet provide a sufficient platform for a detailed analysis. Only a few of the publications available deal with non-genetic adaptation exclusively; many are primarily devoted to other topics. The mechanisms of most types of adjustments appear to be rather complex and are not yet well understood. The net result of non-genetic adaptation is compensation for adversive aspects in a changing environment. 2. Non-genetic adaptation may involve quantitative changes in lethal limits, activity, metabolism, reproduction and other functions as well as in body dimensions, architecture of organs and cells, cell number per organ and in the quantity and activity of enzymes. It practically involves all levels of organismic function and structure. Non-genetic adaptation is not the result of a single process but represents a syndrome. The capacity for non-genetic adaptation depends on the genetic background of the organism involved; it may be different in different ontogenetic stages, such as egg, larva and adult, and may bear relations to metamorphosis and reproduction. There appears to be some evidence that non-genetic adaptations which have been acquired during the most sensitive phase of an individual's life cycle may be transferred to the next generation as non-genetic transmission (e. g.Prosser 1958). 3. There is urgent need for carefully conducted long-term experiments. Much of our present knowledge on non-genetic adaptation has been obtained from organisms kept under inadequate conditions; numerous experiments seem to have been conducted on sick or dying specimens. Even the small amount of information available at this time has therefore to be evaluated with some critical skepticism. Poor conditions and poor health are dangerous prerequisities for the analysis of such a complex and subtle process as is non-genetic adaptation. 4. Assessment of quantitative aspects of non-genetic adaptation requires distinction between its amount, stability and velocity. To illustrate this point, let us consider a euryplastic organism with a considerable capacity for non-genetic adaptation. In such an organism the amount of non-genetic adaptation tends to reach the highest values during early ontogeny and thereafter to decrease gradually with increasing age of the individual. The maximum amount of a given acclimation may only be attainable in individuals born and raised in the test environment. The amount may be expressed in “percentage perfection”. The perfection of a nongenetic adaptation is 100 per cent in the rare case of an “ideal” or “perfect” acclimation, i. e. if the steady-state performance following a significant change in temperature or salinity goes back to its original level after stabilization. In most cases the percentage perfection is much smaller. Thus in the crabPachigrapsus crassipes perfection of acclimation to a seasonal range of about 10°C (Southern California) was calculated byRoberts (1957) from rate-temperature curves for individuals acclimated to experimental temperatures to be about 30 per cent. The degree of stability of a non-genetic adaptation, too, seems to decrease with increasing age: adjustments during early ontogenetic development tend to be more stable than those performed during later periods of ontogeny and may even be — at least in part — irreversible throughout the rest of the life of the individual concerned. Examples areCrangon crangon (Broekema 1941),Gammarus duebeni (Kinne 1953, 1958b),Lebistes reticulatus (Gibson 1954,Fry 1957,Tsukuda &Katayama 1957,Tsukuda 1960),Cyprinodon macularius (Kinne 1962). Reversible acclimations need reinforcement if they are to be maintained. The velocity of non-genetic adaptation tends to increase with increasing rates of metabolism. In the fishCyprinodon macularius, for example, speed of acclimation increases with temperature and seems to be proportional to growth rate: fast-growing fish adapt faster than slow-growing ones (Kinne 1960, 1962). 5. Most authors have considered non-genetic adaptations to a single environmental factor, namely either to temperature or salinity. Organisms, however, react to their total environment rather than to single entities. It is therefore of particular importance to study the combined effects of two or more components of the environment. Very little is presently known about the combined effects of temperature and salinity on the process of non-genetic adaptation (e. g.Dehnel 1960,Todd &Dehnel 1960,Matutani 1962,Alderdice 1963,Kinne 1963b, 1964a, b).McLeese (1956) analyzed the combined effects of temperature, salinity and oxygen on the survival rates of American lobsters (Fig. 8) (see alsoAlderdice 1963), and at the present Symposium,Roberts (1964) reported that the perfection of thermal acclimation of respiration in sunfishLepomis gibbosus becomes a function of day length above temperature of about 10°C. 6. There appears to be some evidence that acclimation to one factor, say salinity, proceeds at different rates and at different efficiencies under different levels of other simultaneous acclimations, for example, to temperature or oxygen (Kinne 1964a, b). Furthermore, inharmonious interrelations between one functional or structural adaptate relative to another may be a fundamental way of limiting the total resulting amount of non-genetic adaptation. The maximum amount of acclimation to a given temperature is presumably only attainable at normal or near optimum salinities, and, conversely, maximum acclimation to salinity is presumably only possible under corresponding temperature conditions. 7. Very little is known about the process of de-adaptation. Does the process of de-acclimation display a similar or a different time course than the respective acclimation? Can de-acclimation from one factor, such as temperature, be initiated or hastened by applying a new stress, such as extreme salinity? De-acclimation may involve active changes and not just a cessation of a given non-genetic adaptation. Thus upon return from high altitude to sea level, erythropoiesis not only stops, but erythrocyte destruction is accelerated (Merino 1950). Apparently, acclimation and de-acclimation are two opposed processes in competition, reaching equilibrium only under constant environmental conditions. 8. The information presented in this paper pertains to reactions of intact, whole individuals. Can we expect cells, tissues or organs removed from multi-cellular animals to preserve and display the full amount of a given non-genetic adaptation acquired in the intact organism? Presumably not, if a substantial part of that acclimation is based on adjustments in organismic integration. But even in other cases, removed cells or organs may often tend to lose part or all of the acclimation acquired due to damages caused by operation procedures. Another important question is whether or not there exists a relationship between the amount of acclimation retained in isolated cells and (a) the level of organismic organization of the test organism (e. g. in the series plant, protozoan, crustacean, fish), or (b) the degree of disturbance caused by the removal of these cells. 9. The amount of cellular acclimation to a given environmental situation may very well be different in different tissues or organs. Thus non-genetic adaptation to changes in salinity may express itself in cells of epidermis, gill or gut rather than in muscle or nerve cells. InCordylophora caspia, for example, acclimation to different salinities results in considerable adjustments in the cells of tentacles, hydranth body and “neck”, while those of the hydrocaulus and stolons remain practically unaffected (Kinne 1958a), and in male rats, cold acclimation causes a remarkable increase in the amount of brown fat, while other tissues do not seem to show such intensive modifications (Smith 1964).

In a previous paper (COCHE, 1967), results concerning the salinity tolerance of coho salmon fry were presented. The present study deals with the ability of yearlings to dispose of the chloride they passively absorb when abruptly transferred from fresh to salt water . Coho salmons normally reside one year in the stream where they were born, the majority of them migrating seawards in the spring of their second year . At this time, they average 12 cm in length and important morphological and physiological changes (smoltification) occur, which prepare the juvenile salmon to be successful in their new environment, the ocean (MALIKOVA, 1957). At this stage of their life, they are capable of passing from fresh water to sea-water, approximately 30 p.p.th. total salt content . The general problem of osmoregulation in fish was reviewed by BLACK (1951a and 1957). But very few studies have been published concerning the osmotic regulation of juvenile coho . BLACK (1951 b) experimented with coho and chum fry . Personally (COCHE, 1967), we made a preliminary study of the survival of coho fry, when transferred from fresh water into sea-water solutions of various salinities . Salinity acclimatization was also tested .

Enchytraeus albidus was fed with Fucus, green algae, Zostera marina and Delesseria. Judging from absorption of food, rate of reproduction and duration of life, the animals preferred the plants in the sequence given above.As the putrefaction of a Fucus substrate advances, more and more enchytraeids leave it. A changing salinity of the substrate also influences the number of emigrating worms, increasing it from 15-45‰, but decreasing it towards 60‰. Fed with Fucus E. albidus tolerates a salinity of 60-70‰ on sand for more than 4 weeks, on filter paper only 50‰ for about one week.Reproduction is possible at salinities up to 40‰. Cocoon production is most frequent at 5‰. The mortality of young worms within the cocoons is lowest at 15‰. The incubation period is significantly shorter at salinities of 0-15‰ than at 30 and 40‰.As a terrestrial immigrant to the seashore Enchytraeus albidus secondarily enlarged its range of poikilosmosis, tolerating a concentration of 72‰ in its coelomic fluid for some time. At low salinities it maintains a remarkable degree of hyperosmosis.

1. In the Gullmarsfjord (west coast of Sweden), an area affected by paper- and pulp-mill wastes was studied. 2. In the interstitial water separated by centrifuging, a relatively high salinity was found. In the studied topmost 8 cm of the sediment, the salinity increased distinctly downward. 3. The polluted sediments, containing wood fibre, had high calcination losses and great contents of interstitial water. This water had a low pH and great KMnO4 consumption. 4. Disappearance of the bottom fauna on the most heavily polluted area and the moving of the maxima of the faunal parameters during a period of 35 years are demonstrated.

This paper presents facts and problems related to the concept of critical salinity, i.e., the salinity range 5 to 8‰ S. It points, in particular, to the distribution of marine and freshwater species revealing a faunistic boundary (minimum number of species), organismic resistance to salinity, osmoregulative capacity, physiological activity, electro-chemical properties of tissues, and evolutionary aspects. The concept of critical salinity opens up new perspectives for the understanding of present day salinity effects as well as for the interpretation of animal evolution.

The common Pacific coast mudstone boring bivalve Adula californiensis (Phillippi) 1847 is useful for laboratory studies on molluscan development. It is in spawning condition from June through October in Oregon, USA. It is easily reared in the laboratory by the methods described in this paper, and its development is typical of the group. A description of major features of early development and the effect of temperature and salinity on developmental rate is given. At 33.2‰ S and 15°C, the first and second cleavages take place 1 1/2 and 2 1/2 h after fertilization. The trochophore stage is reached in 15 h and the shell gland becomes apparent at 31 h. By 72 h, the larval shell completely encloses the soft parts. Developmental rate increases linearly with temperature. Lowered salinity retards developmental rate, and development is abnormal below 26.3‰ S. Larvae do not congregate at salinity interfaces, but avoid low salinities in gradient experiments. Veligers swim rapidly and vertically in both directions, but show no ability to swim horizontally. After 3 days in laboratory culture, the larvae settled and survived for long periods of time; metamorphosis did not occur, however.

Seasonal variations in temperature, dissolved oxygen and salinity have great influence upon marine life. However, these factors incidental to the tropical environment have not been fully investigated. In this paper some effects of a sudden change in temperature as well as the effects of various partial pressures of oxygen upon its uptake are presented with reference to Chanos chanos-the milk fish, so widely used in fish culture. An attempt has also been made to relate this study to a limited range of size of the fish.

This paper deals with studies on temperature, salinity, turbidity, phosphate, silicate, nitrate, chlorophylla and zooplankton in the Patuxent River Estuary for a 20-month period from July 1963 to February 1965.

IN recent numbers of NATURE there have appeared two communications which seem to call for comment. In the issue of August 22, Lowndes1 discusses the question of the water content of medusae, determining that of Aurelia aurita to be 96.56 per cent in sea water of 3.3 per cent salinity. A few years ago I became interested in the same question and also determined the water content of Aurelia aurita, finding 96 per cent water in specimens from sea water of 3.2 per cent salinity2. Later, I determined the water content of four other species of medusae, all hydromedusae, finding 96.5–97 per cent water in specimens taken from sea water of 3.0 per cent salinity3. In the first of these papers I reviewed the available data on the subject4 ; these show that in sea water of more than 3 per cent salinity, the water content of medusae ranges from 94 to 96.5 per cent but that in brackish water of less than 2 per cent salinity, the water content of Aurelia aurita may rise to 98 per cent. From these facts it may be inferred that the water content of freshwater medusae must be very high, and this has recently been found to be the case by Dunham5, who reports 99–99.3 per cent water in Craspedacusta, thus confirming an old statement by Cremer6.