Showing papers in "The Biological Bulletin in 1950"
TL;DR: A series of arctic and tropical mammals and birds at Point Barrow, Alaska and in Panama was subjected to various air temperatures in a respiration chamber where the heat production was determined by oxygen consumption or carbon dioxide production.
Abstract: A series of arctic and tropical mammals and birds at Point Barrow, Alaska (lat. 71° N.) and in Panama (lat. 9° N.) was subjected to various air temperatures in a respiration chamber where the heat production was determined by oxygen consumption or carbon dioxide production. The larger arctic mammals and birds showed no increase in metabolism at — 30° C. and from observations on sleeping animals it is probable that their zone of thermoneutrality extends to — 40° C. or — 50° C. The smaller arctic species show a high critical temperature and the tropical species even higher. Metabolic heat production increases rapidly with lowering of the temperature in a tropical mammal or bird, and slowly in an arctic animal. It can be shown theoretically that in a thermoregulated system with a fixed basal energy level and variable insulation the critical gradient is proportional to the maximal insulation and the basal energy level.In a large series of experiments including our tropical and arctic animals, and all animals ...
776 citations
TL;DR: Insulation measurements on raw skins from 16 arctic and 16 tropical mammals are given and there is, as would be expected, a good correlation between the thickness of the fur and the insulation.
Abstract: Insulation measurements on raw skins from 16 arctic and 16 tropical mammals are given. There is, as would be expected, a good correlation between the thickness of the fur and the insulation. The smaller arctic mammals (weasels, lemmings) have much less insulation than the larger and overlap many of the tropical forms. From the size of a fox to the size of a moose there is no correlation between insulation and body size, they all have about the same insulation per surface area. When submerged in ice water, seal blubber retains about the same good insulation, as compared with measurements taken in 0° C. air. In the polar bear, heat transfer through the fur increases 25-50 times when submerged, because of complete wetting of the skin surface and absence of blubber. The beaver is slightly better off when submerged, as it retains an insulating layer of air in the fur next to the skin.
576 citations
TL;DR: There is no evidence of adaptive low body temperature in arctic mammals and birds, or highBody temperature in tropical mammals andbirds.
Abstract: Maintenance of constant body temperature in a homoiothermic animal depends upon a balance between heat production and heat dissipation, and there are consequently three possible main avenues for climatic adaptation, (1) by body-to-air gradient, (2) by heat dissipation, and (3) by metabolic rate. There is no evidence of adaptive low body temperature in arctic mammals and birds, or high body temperature in tropical mammals and birds. The body-to-air gradient can be adapted only by means of behavioral thermoregulation (nest building, avoidance of direct sunshine, etc.). With few exceptions our adult arctic and tropical mammals and birds have a basal metabolic rate that fits the standard mouse to elephant curve, i.e., the basal metabolic rate is determined by an exponential relation to size; evidently fundamental to most animals, warm-blooded or not. The basal metabolic rate is consequently not influenced by such factors as temperature gradient and insulation which largely determine the heat loss, and is henc...
564 citations
TL;DR: A close relationship is noted between the role of the phagocytes in the normal digestive process and in the "defense" re-defense of the oyster.
Abstract: The responses of the oyster to an intracardial injection of a sea water suspension of india ink were followed grossly and microscopically. The ink suspensions agglomerated readily and produced emboli which virtually occluded the arterial vessels of viscera, mantle and adductor muscle. Subsequent events, with considerable overlapping, were in sequence : (a) phagocytosis of the injected ink particles by mobile phagocytes, (b) distribution of the ink in the phagocytic amebocytes to all parts of the organism with concomitant resolution of the emboli and (c) eventual elimination of the ink from the organism by the migration of ink-laden phagocytes through the epithelial layers of the alimentary tract, digestive diverticula, palps, mantle, heart and pericardium into lumina from which they were voided. The epithelia of gonaducts, nephridia and shell-forming mantle were not routes of migration. A close relationship is noted between the role of the phagocytes in the normal digestive process and in the "defense" re...
109 citations
TL;DR: The simple but efficient method described in this article for conditioning the hard shell clam, V. mercenaria, to spawn out of season and for culturing its larvae will be applicable to many other species of lamellibranchs permitting their successful cultivation in the laboratory, where their morphological features and various aspects of behavior can be studied under controlled conditions.
Abstract: Rapid progress in studies of the morphology, physiology and ecological requirements of lamellibranch larvae, as well as other forms, can be achieved only if these organisms are easily available for study. This is seldom so in the case of lamellibranchs because the majority have a breeding period of comparatively brief duration lasting only a few months (Lebour, 1938; Thorson, 1946). During this period the larvae can be collected in plankton tows but, unfortunately, the early stages of many lamellibranchs are so alike in size and appearance that it is often impossible to distinguish with any degree of certainty the larvae of different species, or even genera. Thus, unless these larvae can be grown to metamorphosis their specific identity may remain in doubt. It is preferable, therefore, to work with larvae raised in the laboratory from fertilized eggs because in that case their identity cannot be questioned. In obtaining material for morphological and physiological studies of larvae the advantages of the direct method, i.e., the method of raising larvae in the laboratory, over the indirect method of collecting them in plankton and often only guessing their identity, are clear. However, because lamellibranch larvae are small, and because their free-swimming period is relatively long, they are difficult to culture. As a result, with the exception of a few successful attempts, mostly confined to commercially important species, such as oysters and mussels, few lamellibranchs have been grown in laboratories past the early veliger stage (Thorson, 1946). Therefore, the need for a simple but reliable method for culturing them is, of course, obvious. It is hoped that the simple but efficient method described in this article for conditioning the hard shell clam, V. mercenaria, to spawn out of season and for culturing its larvae will be applicable to many other species of lamellibranchs permitting their successful cultivation in the laboratory, where their morphological features and various aspects of behavior can be studied under controlled conditions. Realizing the importance of having a good supply of larvae for studies of the life history of Venus mercenaria, Belding (1912) tried to raise them in the laboratory. He was not successful because most of the larvae in his cultures died either before they reached the straight hinge veliger stage or soon afterwards. Belding concluded that there was no practical method for raising hard shell clams to the setting stage because of the small size and delicate nature of the eggs. Several years later, nevertheless, Wells (1927) succeeded in growing clam larvae to the setting stage. Wells, however, was mostly interested in oysters and did not continue the clam work.
88 citations
TL;DR: The ectoderm of the early gastrula of Triturus pyrrhogaster was isolated and exposed for a short time to a solution of ammonia and then cultured in Holtfreter solution, resulting in the development of the blood island, mesothelium and blood vessels was almost completely suppressed.
Abstract: (1) Control series I. The ectoderm of the early gastrula of Triturus pyrrhogaster was isolated and exposed for a short time to a solution of ammonia and then cultured in Holtfreter solution. The isolate differentiated structures which can be characterized as cephalic ectodermal rudiments including brain, eye. nose and frontal glands. Otic vesicles, spinal cord and mesodermal structures were wholly absent.(2) Control series II. The ventral marginal zone of the early gastrula was isolated and cultured in Holtfreter solution. It differentiated blood island, blood vessels and mesothelium and nephric tubules.(3) Experimental series. The isolated ventral marginal zone was treated with ammonia solution and cultured in Holtfreter solution. It gave rise to notochord and muscle as well as nephric tubules. The development of the blood island, mesothelium and blood vessels was almost completely suppressed.(4) Results were interpreted from the standpoint of the double-potential theory (Yamada, 1947).
86 citations
TL;DR: Thirty sugars and related compounds have been tested on the blowfly Phormia regina Meigen to determine their nutritive value for this species and their effectiveness as stimuli for the tarsal receptors.
Abstract: Thirty sugars and related compounds have been tested on the blowfly Phormia regina Meigen to determine their nutritive value for this species and their effectiveness as stimuli for the tarsal receptors.Survival tests indicated that all pentoses except fucose are utilized to some extent. Xylose and ribose are the best. The hexoses are almost uniformly good. Sorbose is the exception. Maltose is the most effectively utilized disaccharide. Sucrose and trehalose are good; melibiose, intermediate; lactose and cellobiose, poor. The trisaccharides melezitose and raffinose and the alcohol sorbitol are effective. In general the polyhydric alcohols are poor.The stimulating effectiveness of the sugars when applied to the tarsi is as follows: disaccharides—sucrose = maltose > trehalose > cellobiose > lactose; monosaccharides—fructose > fucose = glucose = D-arabinose = sorbose > D-xylose = L-xylose = galactose = L-arabinose > mannose = ribose > lyxose.There is no good correlation between the nutritive value of these co...
83 citations
TL;DR: A Cartesian diver method which is specially adapted for following variations in respiratory rate of small objects is described, which can be obtained every few in minutes.
Abstract: A Cartesian diver method which is specially adapted for following variations in respiratory rate of small objects is described. Accurate respiration measurements can be obtained every few inminutes. The diver is calibrated empirically and it is filled free-hand.
76 citations
TL;DR: Lymnaeidae and Physidae tolerated complete lack of oxygen less well than Planorbidae or operculates belonging to different families and produced carbon dioxide and lactic acid under anaerobic conditions.
Abstract: 1. Lymnaeidae and Physidae tolerated complete lack of oxygen less well than Planorbidae or operculates belonging to different families.2. All species consumed carbohydrate under anaerobic conditions and produced carbon dioxide and lactic acid. While in several species the lactic acid produced was sufficient to account for all or a large part of the carbon dioxide as liberated from bicarbonate, this was not the case in other species.3. The anaerobic metabolic level as measured by carbon dioxide production and carbohydrate consumption of the resistant species was, on an average, lower than that of the nonresistant ones. The former did not accumulate lactic acid within their tissues during an anaerobic period, while the latter did so to a marked degree.4. In most species the anaerobic carbohydrate consumption was only slightly higher than the aerobic rate. One of the reasons for this may be the probable occurrence of aerobic fermentations in these species.5. Lactic acid was quantitatively a major end product...
73 citations
TL;DR: In this article, the authors developed an approach to determine whether commensals of the polynoid genus Arctonoe are attracted by specific substances to their hosts and whether they can distinguish between water coming from an aquarium containing their host and sea-water alone or water from non-host.
Abstract: 1. Apparatus was developed which made it possible to determine whether commensals of the polynoid genus Arctonoe are attracted by specific substances to their hosts and whether they can distinguish between water coming from an aquarium containing their host and sea-water alone or water from non-host.2. Arctonoe fragilis (Baird) commensal with the star Evasterias troschelii Stimpson are clearly attracted to their host and can distinguish between water coming from their host and sea-water alone. Arctonoe (pulchra-vittata?) commensal with the cucumber Stichopus are likewise attracted to their host.3. Arctonoe fragilis commensal with Evasterias are not attracted to the non-host star, Pisaster, occurring in the same immediate environment as their host. Arctonoe (pulchra-vittata?) commensal with the cucumber Stichopus are likewise not attracted to the non-host Cucumaria.4. Arctonoe (pulchra-fragilis?) commensal with the mud-star Luidia are not attracted, under these experimental conditions at least, to their ow...
66 citations
TL;DR: This review deals with the general question of relation of metabolic activities to cleavage in the Arbacia egg and the nature and interrelatio...
Abstract: 1. This review deals with the general question of relation of metabolic activities to cleavage in the Arbacia egg. According to current biochemical concepts the answer to this question would be found in complete information about the following subjects:a. The identity and interrelationships of the catalysts by which the eggs derive energy from foodstuffs.b. The reactions by which energy is transferred to make possible the synthesis of structural and functional elements of the egg, such as carbohydrates, proteins, lipids, coenzymes, nucleic acids and other substances, many of which may yet be unknown.c. The chemical and Physical chemical rearrangements of these structural functional elements which lead to the biological event of cleavage.The third subject is completely beyond investigation by present techniques, and the second is just being opened to investigation in the living egg by application of isotopic labelling techniques. This review is concerned, therefore, chiefly with the nature and interrelatio...
TL;DR: The metabolism of fish brain tissue increases rapidly between 0° and 27°, but at higher temperatures the increase with temperature is less marked and at the highest temperature may be lower again, while logarithmic plots of the metabolism of brain tissue and of whole animal respiration are similar in slope.
Abstract: 1. Oxygen consumption of goldfish at acclimatization temperatures increases between 12° C. and 27° C. but is again lower at 37.8° C.2. When measured at a single temperature, there is an inverse relation between oxygen consumption of brain breis and the acclimatization temperature of fish between 12° and 37.5° C. The level of oxygen consumption of muscle breis, however, does not differ significantly for fish acclimatized at 12° and 27° C.3. When measured over the range from 0° to 37.8° C., the metabolism of fish brain tissue increases rapidly between 0° and 27°, but at higher temperatures the increase with temperature is less marked and at the highest temperature may be lower again.4. At temperatures up to 27° C., logarithmic plots of the metabolism of brain tissue and of whole animal respiration are similar in slope.5. Between 4° and 27° C., the rate of opercular movements at the acclimatization temperatures increases with temperature just as does the rate of brain tissue metabolism calculated for the acc...
TL;DR: Under conditions of constant darkness the red chromatophores of Uca pugilator show a striking persistent daily rhythmicity, dispersing their pigment by day, and concentrating it by night.
Abstract: 1. The red chromatophores of Uca pugilator, when other factors are equal, exhibit extensive responses to background. They disperse their pigment upon a black background, and concentrate it upon a white one.2. Under conditions of constant darkness the red chromatophores show a striking persistent daily rhythmicity, dispersing their pigment by day, and concentrating it by night.3. Extracts of sinus glands, and all of the major portions of the central nervous system, possess strong activity upon the red chromatophores. All portions exhibit two types of activity due to the possession of two principles. One of the activities is red-concentration and the other, red-dispersion.4. The action of the red-concentrating principle can dominate the response when there is, concurrently present, high concentrations of both red-dispersing and red-concentrating principles.5. The red-concentrating activity of all extracts is of much shorter duration than is the red-dispersing activity, the latter often lasting 3 to 4 times ...
TL;DR: Enrichment cultures of Synechoccus elongatus Nag.
Abstract: 1. Enrichment cultures of Synechoccus elongatus Nag., a unicellular blue-green alga, carry out photosynthesis in a carbon-dioxide-bicarbonate buffer with a quotient of 1.08 ± .03.2. This alga has a hydrogenase which can be activated anaerobically in the presence of molecular hydrogen. In the light, adapted algae can carry out photoreduction.3. In contrast to Scenedesmus, activation of the hydrogenase can be carried out at low light intensities.
TL;DR: Of the animal population of the sea, three groups seem considerably more probable than any others, namely, fish, squid, and crustacea, and if experimental tests now in progress show that the crustacea meet the acoustical requirements, then there will be little reason to consider either fish or squid.
Abstract: The source of the scattering effect is not, at present, susceptible of direct proof, but if an organism could be found whose characteristics agreed with those of the layer on a sufficient number of points, then there would be a high probability that this is the actual source of the effect. From the diurnal migration of the layer there seems no room for doubt that it is caused by an animal. Of the animal population of the sea, three groups seem considerably more probable than any others, namely, fish, squid, and crustacea. There are certain arguments which make the latter the most likely, and if experimental tests now in progress show that the crustacea meet the acoustical requirements, then there will be little reason to consider either fish or squid.Of the crustacea, the small copepods may prove to be the source of shallow reverberation and possibly some very shallow layers. Euphausid shrimps are the dominant crustacean at the depth of the main scattering layer. These and large red prawns are the dominan...
TL;DR: The effects of metabolic inhibitors on the development in vitro of approximately 600 chick blastoderms (definitive primitive streak through 8-somite stages) have been studied.
Abstract: 1. The effects of metabolic inhibitors on the development in vitro of approximately 600 chick blastoderms (definitive primitive streak through 8-somite stages) have been studied.2. Embryos explanted to glucose media containing either 10-4 to 5 x 10-5 M monoiodoacetate or 10-2M fluoride rapidly undergo complete degeneration and disintegration. These effects are reversible by substitution of 2 x 10-2M pyruvate (or lactate) for the glucose. At lower inhibitor concentrations of iodoacetate (2 x 10-3M) the central nervous system degenerates or fails to form, but the heart develops and pulsates. Fluoride has almost the opposite effect: concentrations which cause degeneration of the heart (5 x l0-3M) have no appreciable effect upon the developing central nervous system.3. Other inhibitors: citrate, malonate, cyanide and azide, produce a differential pattern of inhibition similar to that produced by iodoacetate. Azide, however, does not lead to as clear cut a pattern of differential degeneration. as do the others...
TL;DR: Zygotes formed from ultraviolet injured eggs are more readily photoreactivated than the unfertilized eggs, and Wavelengths shorter than λ4300A are most effective in photoreactivation.
Abstract: 1. Ultraviolet radiation induced cleavage delay in eggs of the sea urchin Strongylocentrotus purpuratus can be reduced by exposure to visible light before fertilization.2. Photoreactivation by visible light occurs in injury by any of the wavelengths of ultraviolet light which we tested: λ2450A, λ2537A, λ2654A, λ2804A, λ3025A, λ3130A. The phenomenon is less pronounced at λ2450A than at the other wavelenths tried.3. Wavelengths shorter than λ4300A are most effective in photoreactivation. The minimum visible light exposure giving an effect near maximal is determined.4. Zygotes formed from ultraviolet injured eggs are more readily photoreactivated than the unfertilized eggs.5. Ultraviolet irradiated eggs show no increase or decrease in injury when kept in the dark for several hours before fertilization.6. Visible light is injurious to sperm.7. Sperm injured by ultraviolet radiations can be photoreactivated, even though the visible light is itself harmful.8. The results are compared with photoreactivation data...
TL;DR: The chloride: excreting cell is not limited to the gill epithelium, being found in other regions of the headrespecially the inner surface of the operculum, and the population density of the chloride cells is in positive ratio to the vascularity of the tissue.
Abstract: 1. The chloride: excreting cell is not limited to the gill epithelium, being found in other regions of the headrespecially the inner surface of the operculum.2. With one exception, the cells appear identical in morphology and in response to Regand-Altmann, Ludford, and alkaline phosphatase techniques. The exception is that the mitochondria are usually more densely packed in the branchial cells.3. In the operculum, the population density of the chloride cells is in positive ratio to the vascularity of the tissue. Such a topographical positioning of the cell is significant to its function of removing chlorides from the circulatory system.
TL;DR: Experiments designed to give some insight into the nature of polarity were performed on the amoeboid slime mold Dictyostelium discoideum, and it was shown that the internal parts do not reflect the external polarity.
Abstract: Experiments designed to give some insight into the nature of polarity were performed on the amoeboid slime mold Dictyostelium discoideum. The separate myxamoebae which stream together to form aggregations of myxamoebae show an external polarity and the resulting cell mass has a clear over-all antero-posteriority. In both cases it was shown that the internal parts do not reflect the external polarity. It is known from previous experiments that the aggregating myxamoebae orient in a concentration gradient of a chemical substance tentatively called acrasin, and that acrasin is found in later stages of development. By reversing the gradient of acrasin, separate myxamoebae did not back up but re-oriented towards the point of high concentration. However, it was shown by various experiments that the external acrasin gradient cannot always determine the direction of the polarity, for in the cell masses the polar movement occurs when there is no external gradient of acrasin, or in some cases away from the region o...
TL;DR: Respiratory metabolism has been studied in brain and liver tissues of two species of fish of similar mean body size, the arctic-adapted polar cod and the Golden Orfe, living at environmental temperatures of – 1.5 to + 2.0° C.
Abstract: 1. Respiratory metabolism has been studied in brain and liver tissues of two species of fish of similar mean body size, the arctic-adapted polar cod (Boreogadus saida), living at environmental temperatures of – 1.5 to + 2.0° C., and the Golden Orfe (Idus melanotus), living at an environmental temperature of 25° C. Experiments were carried out in the Warburg apparatus over the range 0-25° C.2. Oxygen consumption in tissues of the Orfe was constant at all temperature levels studied for 180-240 minutes. In tissues of the polar cod, oxygen consumption was constant for 5-6 hours in the temperature range 0-5° C., and then the duration of the steady state decreased progressively as the temperature increased, so that at 25° C. constant oxygen consumption was observed in most cases for no longer than 40 minutes.3. The Q10 for the steady state respiration of tissues of these two species of fish is of the same order of magnitude; values obtained were 2.08 and 2.11, respectively, for polar cod brain and liver, and 2....
TL;DR: Asphyxia of normal Astacus and Callinectes results in marked increase in concentration of blood-sugar; such increase is mediated by sinus glands located in the eyestalks, for after removal of these glands hyperglycemia does not occur after asphyxia.
Abstract: 1. Asphyxia of normal Astacus and Callinectes results in marked increase in concentration of blood-sugar; such increase is mediated by sinus glands located in the eyestalks, for after removal of these glands hyperglycemia does not occur after asphyxia. Hyperglycemic response to asphyxia is part of a reflex mechanism; it does not occur following denervation of the sinus glands.2. Chloroform anesthesia in Astacus similarly evokes rises in glycemic level which fail to occur after sinus gland removal. Since anesthesia brings about cardiac arrest, the resultant anoxia may be the basic explanation of the anesthesiainduced hyperglycemia.3. Adrenaline, in doses from 1 to l00γ, causes hyperglycemia in normal Astacus, but injection into sinus-glandless crayfish shows either no rise in the concentration of blood-sugar, or a very slight one. Similar injections into Callinectes result in marked hyperglycemia in normal individuals, in animals with denervated sinus glands, in sinus-glandless and also in eyestalkless ind...
TL;DR: Eggs of the tubularioanthomedusan, Spirocodon saltatrix, which breeds in the neighborhood of the Misaki Station from the beginning of January to the latter part of March, are spawned daily, shortly after nightfall.
Abstract: Eggs of the tubularioanthomedusan, Spirocodon saltatrix, which breeds in the neighborhood of the Misaki Station from the beginning of January to the latter part of March, are spawned daily, shortly after nightfall. The change from light to darkness causes the initiation of the maturation divisions, at the completion of which the eggs are shed. Spawning can be induced by darkening in the laboratory.In the mature eggs, the pronucleus lies in contact with the surface, at the base of a slight depression at the animal pole. These eggs are fertilizable only when spawned into sea water containing freshly shed spermatozoa.Examination of such eggs with the phase contrast microscope shows that the fertilizing sperm always enters in the immediate vicinity of the egg pronucleus. At the sperm entrance point a tubular structure of transparent substance begins to develop around the sperm tail as soon as the head of the sperm has penetrated the egg. This continues to increase in length and diameter for about five minutes...
TL;DR: While there is no conclusive evidence that there are two separately acting lysins, this is strongly supported by the fact that they are inactivated by trypsin.
Abstract: Extracts of Mytilus sperm contain a lytic substance, or substances, which causes dissolution of the egg membrane and the intercellular cement which binds the blastomeres together. Bioassays were utilized to investigate the occurrence and relationship of the active agents and some of their chemical properties. The lytic effects are exhibited by concentrated sperm suspensions and their supernatants obtained by centrifugation. Extracts prepared by freezing and thawing and by acidification or alkalization exhibit the same relative strengths of lytic activities.The active agents are large molecules, as indicated by their non-dialyzability through cellophane. They are precipitated by ammonium sulfate, by dialysis against distilled water, and by alcohol. These properties indicate a protein nature of the lytic substances, an assumption which is further supported by the fact that they are inactivated by trypsin.While there is no conclusive evidence that there are two separately acting lysins, this is strongly sugg...
TL;DR: Phase contrast microscope observation of sperm penetration into the eggs of five species of sea urchins have shown that total engulfment of the spermatozoan including all of the tail, is the rule in these species.
Abstract: 1. Phase contrast microscope observation of sperm penetration into the eggs of five species of sea urchins—Mespilia globulus, Clypeaster japonica, Strongylocentrotus pulcherrimus, Pseudocentrotus depressus, Heliocidaris crassispina—and one starfish—Asterina pectinifera—have shown that total engulfment of the spermatozoan including all of the tail, is the rule in these species.2. In every case the fertilization cone makes its first appearance after contact has been established between the sperm head and the living egg cytoplasm, and persists in normal cases for from 5 to 15 minutes after the beginning of sperm penetration. Subjection of the eggs to some experimental conditions—heat, cold, nicotine solution—causes abnormal production and persistence of the fertilization cones.3. Engulfment of the sperm tail in these species is usually complete within 2-4 minutes after the beginning of penetration. No significant change in engulfment time could be induced by exposing the eggs to the abnormal physiological co...
TL;DR: This investigation revealed the presence of two different types of leucocytes in Arbacia: trephocytes and phagocytes, no genetic relationship between the two kinds could be established, a circumstance which further tends to prove the distinctive nature of each type.
Abstract: This investigation revealed the presence of two different types of leucocytes in Arbacia: trephocytes and phagocytes. An outline of their morphology, development and physiology is presented. No genetic relationship between the two kinds could be established, a circumstance which further tends to prove the distinctive nature of each type.Particulate matter derived from the trephocytes and essentially of a nutritive nature, is taken up and incorporated by the growing oocytes. A considerable fraction of this material has its origin in the red trephocytes which contain echinochrome. It is suggested that the echinochrome found in the eggs of the species investigated may also be derived from the trephocytes.The occurrence of respiratory pigments among invertebrate trephocytes is discussed. It is pointed out that the erythrocytes of invertebrates, as well as the early stages of those of vertebrates, exhibit characteristics of trephocytes. The idea is advanced that the erythrocytes represent a special kind of tre...
TL;DR: The varying number of pits in fresh and sea water adapted animals is correlated with the findings from previous physiological studies of osmotic adaptation.
Abstract: 1. The shape of the chloride cells in the gill of Anguilla rostrata varies with their position in the filament. The cells along the free edge have a thin, spindle shape, while those at the bases of the respiratory platelets are more round.2. Eels adapted to sea water exhibit narrow pits at the free surface of the chloride cells that are located along the afferent artery.3. The presence of many pits is characteristic of sea water adaptation, but animals adapted to fresh water also possess an occasional pitted cell.4. The varying number of pits in fresh and sea water adapted animals is correlated with the findings from previous physiological studies of osmotic adaptation.
TL;DR: The ovum and egg-case of Mustelus canis, a viviparous elasmobranch, are described and the orientation of the egg- case in utero is noted and it is probable that as a rule two ova are discharged simultaneously.
Abstract: 1. The ovum and egg-case of Mustelus canis, a viviparous elasmobranch, are described and the orientation of the egg-case in utero is noted.2. The blastoderm is typically located near the cloacal end of the yolk and the dorsal lip of the blastopore forms at the anterior border of the blastoderm when the egg is oriented as it lies in utero. Occasional cases of reversed and oblique orientation are found.3. In early June, mature females are post-partum. The functional right ovary contains large ova soon to be ovulated while the left ovary is vestigial.4. The ovulation period extends from about June 20 to July 20. Four to eight ova are generally found in each uterus of a pregnant female and, from a comparison of stages present, it is probable that as a rule two ova are discharged simultaneously with an interval tentatively estimated at 30 to 40 hours between most subsequent ovulations.5. Ova are arranged in sequence in each uterus with the most advanced embryo nearest the cloacal end.6. Stages of embryos prese...
TL;DR: Oscillographic records are presented of the sounds produced by Drosophila funebris during "fixed" flight and analysis of these sounds suggests a remarkable aerodynamic efficiency for the wingbeat cycle.
Abstract: 1. Oscillographic records are presented of the sounds produced by Drosophila funebris during "fixed" flight. Stroboscopic determinations of wingbeat frequency indicate that one cycle of wing motion corresponds to one cycle of flight sound.2. The sounds generated during flight are complex and radically different from the simple harmonic motion of a tuning fork. Certain consequences of this fact are discussed.3. Analysis of these sounds suggests a remarkable aerodynamic efficiency for the wingbeat cycle. The flying insect produces a polarized flow of air from front to rear during approximately 85 per cent of the wingbeat cycle.4. During brief periods of flight the first few and the last few beats of the wings are accomplished at the high frequency characteristic of the entire flight. This fact is considered in relation to Pringle's new observations concerning the neuromuscular system of dipterous insects.
TL;DR: The later divisions in the egg of Psammechinus miliaris are accompanied by variations in oxygen uptake, which is interpreted as an extra O2-uptake correlated with the mitosis.
Abstract: The later divisions in the egg of Psammechinus miliaris are accompanied by variations in oxygen uptake. As in the embryo more and more cells divide simultaneously, the respiratory variations become more and more pronounced. The phenomenon is interpreted as an extra O2-uptake correlated with the mitosis. During the four divisions nos. 58 proportionality is approximated between number of cells dividing and extra O2 taken up. Thus, for the division period considered, the extra O2 consumed by a dividing cell approximates constancy, viz.: it is independent of the size of the dividing blastomere.