Water Oxygen Consumption Research Articles

Вплив іонів Cu (II) на легеневе й поверхневе дихання аловидів Planorbarius corneus s. l. (Mollusca, Gastropoda, Pulmonata) гідромережі України

One of the urgent problems of modern hydroecology is an increasing pollution of Earth hydrosphere by heavy metal ions. The necessity of this problem’s solution within Ukrainian river network is caused by the recent intensification of polluting of its surface waters by these pollutants. That is why the identification the species-indicators for level of pollution by Cu (II) ions in nature water bodies among the most widespread and numerous Ukrainian mollusks is an expedient task. We aimed at question: whether or not the great ramshorn, the only representative of genus Planorbarius Dumeril, 1806 in Northern hemisphere, can be assigned to such a category? For this purpose, we establishedof the influence of Cu (II) ions within the concentrations of 0.5 MPC to 3 MPC were studied on the indicators of lung and direct surface diffusive respirations of the “western” and “eastern” genetic vicaristic allospecies of great ramshorn Planorbarius corneus s. l. in the hydrological river network of Ukraine. These mollusсs, like all Pulmonata, have a bimodal respiration pattern. They use their true lungs for atmospheric oxygen breathing and the diffusive (surface) respiration is used for soluble in the water oxygen consumption. The aim of present study was to clarify the features and difference levels of lung and surface diffusive respiration of “western” and “eastern” allospecies under the impact of Cu (II) ions in water environment (MPC: 0,5, 1, 2, 3). It was established that the endurance coefficient for concentrations Cu (II) in water environment appeared lower in “eastern” allospecies to those in “western” allospecies. Under the same concentrations of toxicants used the lethality of “eastern” allospecies was higher than that of “western” allospecies in all cases. The indexec of lung and direct diffusive respiration in the allospecies of great ramshorn P. corneus s. l. under the impact of the Cu (II) ions concentration in water environment demonstrated that “eastern” allospecies tends to regress under the increased environmental pollution more comparing to “western” allospecies (р≤0,05–0,001).

SELECTION OF INDICATIVE INDICATORS OF ECOLOGICAL CONDITION OF SURFACE SOURCE OF WATER SUPPLY

In recent years, there has been an aggravation of problems in the field of environmental safety of surface water sources, which is caused by the unsatisfactory state of water resources. Among the reasons for this should be noted the lack of effective mechanisms for water management, control and responsibility. A comprehensive assessment of the environmental safety indicators of surface water sources of supply by chemical indicators is a laborious task. Indicators are obtained by combining and summarizing many complex indicators into one integrating one, which makes it possible to characterize different positions of water bodies. The practice of monitoring in surface water indicates the need to minimize resources to obtain a comprehensive assessment of the environmental safety of a water object. Therefore, the purpose of this work is to justify the choice as an indicative indicator of the ecological state of the surface source of drinking water supply of biochemical oxygen consumption. To do this, it is necessary to characterize the ecological state of the studied area using the combinatorial index of water pollution and establish a link between this index and biochemical oxygen consumption. The calculation of the value of the combinatorial pollution index and the relative assessment of the ecological state of surface water were carried out in two stages: first, for each individual investigated substance and indicator of the ecological state of surface water, then the entire complex of pollutants was considered simultaneously and the resulting assessment was derived. Baseline indicators play an important role in the ecology of a water object. Therefore, the content of dissolved oxygen and biochemical oxygen consumption in water is of great interest not only in terms of the development of life, but also as an indicative indicator of the ecological state of the aquatic environment, makes the indicator of biochemical oxygen consumption important for indicative assessment of water pollution by various organic substances. For the tasks for which we justify the choice of indicative indicators of the ecological state of surface water, it is more important to identify the consequences of pollution not directly at the site of pollution, but at some distance from it and after a while. Therefore, the use of the amount of dissolved oxygen and biochemical oxygen consumption as indicators characterizing the oxidation process of existing pollutants in water is the most appropriate for the tasks of operational monitoring of water bodies.

Water Oxygen Consumption Rather Than Sediment Oxygen Consumption Drives the Variation of Hypoxia on the East China Sea Shelf

AbstractSediment oxygen consumption (SOC) is important in modulating the oxygen budget in the East China Sea where seasonal hypoxia occurs. Porewater advection, molecular diffusion and bioturbation supply oxygen for sedimentary organic matter degradation. A pelagic‐benthic coupled model was applied to quantify the SOC. A comparison with observations showed good model performance in reproducing the hydrographic and ecological environments, particularly for the interannual variation in the hypoxic zone. Simulation results show that porewater‐advection‐induced flux is the predominant component of the SOC in sandy areas on the Changjiang bank and outer shelves, while the bioturbation‐induced flux is predominant at mud depocenters. By comparing SOC to the water oxygen consumption (WOC) below the pycnocline, the contribution of SOC is generally below ∼40% in the hypoxic zone. The spatial distribution of SOC in summer is relatively steady from year to year, while the high WOC patches explain more about the interannual variation in the hypoxic zone. WOC rather than SOC drives the variation of hypoxia. Particularly on the Changjiang bank, milder hydrodynamics are favorable for both the higher WOC and bioturbation‐induced benthic oxygen flux but substantially suppress the porewater advective flux, which results in the net lower contribution of SOC to hypoxia. This finding may shed light on other pelagic‐benthic coupling processes in coastal shelf seas where hypoxia occurs on permeable sediments.

Regarding the choice of composite indicators of ecological safety of water in the basin of the Siversky Donets


 
 
 
 The lack of effective mechanisms of the methods of basin management, control of and responsibility for the ecological state of surface sources of drinking water leads to the fact that the main man-made objects that determine the ecological state of surface water sources are most often located in one oblast, while the production and consumption of the drinking water from those sources occur in the territory of other oblasts, which complicates the effective management of environmental safety of surface water sources. This is especially true for the regions of Ukraine which are poor in surface water resources, located in the basin of the Siversky Donets River, the water bodies of which are the main sources of water supply in the eastern regions of the country. The main consumer of water is Donetsk Oblast (over 50 % of the annual volume), and Kharkiv and Luhansk Oblasts together consume approximately the same volume of water per year (up to 50 % of the annual volume). Therefore, it is important to substantiate the integrated indicators of the ecological status of the water body to improve the environmental safety of surface water sources. The paper shows that oxygen indicators play an important role in the ecology of a water body. They are associated with the assimilative ability of water, the ability of water to decompose organic matter. Therefore, the content of dissolved oxygen and biochemical oxygen consumption in water is of great interest not only in terms of life development, but also as a composite measure of the ecological status of the aquatic environment. The relationship between the value of the combined index of water pollution and the value of biochemical oxygen consumption makes the indicator of biochemical oxygen consumption important for the integrated assessment of water contamination with various organic substances. For the tasks for which we justify the choice of composite measures of the ecological condition of surface waters, it is more important to identify the effects of contamination not directly at the site of contamination, but at some distance from it and after some time. Therefore, the use of the amount of dissolved oxygen and biochemical oxygen consumption as indicators that characterize the oxidation of pollutants present in water is the most appropriate for the tasks of timely monitoring of water bodies. Therefore, as a composite indicator for characterizing the condition of the watercourse and conducting timely monitoring, we chose oxygen indicators.
 
 
 

Does FLASH deplete oxygen? Experimental evaluation for photons, protons, and carbon ions.

To investigate experimentally, if FLASH irradiation depletes oxygen within water for different radiation types such as photons, protons, and carbon ions. This study presents measurements of the oxygen consumption in sealed, 3D-printed water phantoms during irradiation with x-rays, protons, and carbon ions at varying dose rates up to 340Gy/s. The oxygen measurement was performed using an optical sensor allowing for noninvasive measurements. Oxygen consumption in water only depends on dose, dose rate, and linear energy transfer (LET) of the irradiation. The total amount of oxygen depleted per 10Gy was found to be 0.04% atm - 0.18% atm for 225kV photons, 0.04% atm - 0.25% atm for 224MeV protons, and 0.09% atm - 0.17% atm for carbon ions. Consumption depends on dose rate by an inverse power law and saturates for higher dose rates because of self-interactions of radicals. Higher dose rates yield lower oxygen consumption. No total depletion of oxygen was found for clinical doses. FLASH irradiation does consume oxygen, but not enough to deplete all the oxygen present. For higher dose rates, less oxygen was consumed than at standard radiotherapy dose rates. No total depletion was found for any of the analyzed radiation types for 10Gy dose delivery using FLASH.

Ratings of Perceived Exertion and Physiological Parameters of Muscle Metabolism in Postmenopausal Women.

We compared responses from postmenopausal women living a sedentary lifestyle ( n = 15; Mean age= 59; SD = 4.2) to a single bout of water- or land-based exercise with respect to ratings of perceived exertion (RPE), lactate concentration, and muscle oxygen saturation. Each participant was randomly assigned to a single water- or land-based 50-minute bout of combined aerobic and resistance exercise. Blood samples were collected to detect pre- and post-exercise lactate concentration. Total hemoglobin, deoxidized hemoglobin, and the percentage change in the total oxygen saturation index (TSI%) of the rectus femoris were detected by means of near-infrared spectroscopy. We found similar RPE at various stages of land- and water-based exercise, and a similar change in lactate concentration in these environments (in water: 4.35 ± 1.49 mol/L; on land: 3.62 ± 1.18 mol/L). However, the reduction in HHb response was less pronounced after water-based exercise, and TSI% increased on land but decreased in water, with the magnitude of this change much higher on land. For similar RPE and lactate concentration, the oxygen saturation in the exercising muscles decreased in water, suggesting higher oxygen consumption in water than on land.

Organic Carbon Composition and Oxygen Metabolism across a Gradient of Seasonally Inundated Limesink and Riparian Wetlands in the Southeast Coastal Plain, USA

A set of three relatively pristine seasonally inundated limesink wetlands and one riparian wetland was studied over a 4–6 month long inundation period in 2001. Patterns in organic matter properties and oxygen consumption in the water column followed a previously documented ecological gradient based on soil composition, vegetation type, and canopy cover. The full canopy, cypress-gum swamp had the highest mean concentrations of dissolved organic carbon (DOC; 26.2 mg/l) and dissolved lignin (sum 6; 299 μg/l) with lower concentrations observed in the partial canopy, cypress savanna (22.0 mg/l DOC; 252 μg/l sum 6) and the open marsh savanna (20.6 mg/l DOC; 135 μg/l sum 6), respectively. During the inundation period, DOC increased in concentration, dissolved lignin decreased, and δ13C shifted to more positive values which collectively indicate a large reduction in the percentage of aromatic carbon during the inundation period. All wetlands had very high concentrations of organic matter, yet microbial oxygen consumption was almost always stimulated by the addition of glucose rather than inorganic nutrients. Stimulation by glucose suggests that there were very small pools of highly bioavailable forms of DOC in the wetlands. A larger pool of moderately bioavailable organic matter had the capacity to sustain microbial oxygen consumption rates under dark conditions for at least 15 d. During the inundation period, the cypress-gum swamp had the lowest average rates of whole water oxygen consumption (1.0 μM/h) with increasing rates observed in the cypress savanna (1.3 μM/h), marsh savanna (1.6 μM/h), and riparian wetland (1.9 μM/h), respectively. The lignin compositional fingerprint varied across the gradient of limesink wetlands, and was useful for identifying different sources of vascular plant-derived DOM. Vascular plant production, algal production, microbial respiration, and UV degradation are all important drivers of DOM cycling, and the consistencies observed in this initial assessment of seasonally inundated limesink wetlands suggest they vary in predictable ways across the ecological gradient.

Experimental Study Assessing the Role of Sedimentary Organic Materials to Control the Redox State of Ground Materials to Control the Redox State of Groundwater: Consumption of Dissolved Oxygen by Humic Acid

Abstract: A total of 189 runs were completed to determine the rate of dissolved oxygen consumption in water by the reaction humic acid at 25°, 45°, and 65°C. Glass vial bottles were used as reaction vessels, and humic aicd and pure water of different intitial O2 concentration was loaded with humic acid/water weight of 0.008 and 0.009. Vials were opened periodically to measure O2 concentrations. The pH of the solution fluctuated in the early stages of the experiments and gradually decreased to a constant value. Dissolved oxygen concentration decreased, for example, from initial value of 12 mg/l to 9 mg/l at 25°C, to 5 mg/l at 45°C, and to 2 mg/l at 65°C after the reaction of 500 hours. Analyses of rates suggest that the reaction is first order, and rate constants are 8.42 × 10‐9 at 25°C, 2.22 × 10‐8 at 45°C, and 1.28 × 10‐7 moles m‐2 s‐1 at 65°C.

Circulatory, acid-base and respiratory responses of the purple shore crab Leptograpsus variegatus to immersion

The supratidal shore crab Leptograpsus variegatus makes use of aquatic as well as terrestrial habitats. The respiratory responses of this species to 12 h immersion in 100% seawater and re-emersion were investigated. The major perturbation was in haemolymph CO 2, the PCO 2 declining to 2.2 torr after 2 h in water compared to >4 torr in air-breathing crabs. Similarly, CCO 2 decreased from 12.8 typical of air breathing to 5.0 mmol · l −1, more typical of water breathing species. This internal hypocapnia promoted an alkalosis which was immediately compensated by a metabolic acidosis that was not a product of anaerobiosis since l-lactate in the haemolymph remained low (0.14 mmol · l −1). When re-emersed, haemolymph CO 2 did not increase to pre-immersion values but, instead, evinced a smaller elevation after 3 h access to air. Control Leptograpsus that could choose between water and air showed intermediate but more variable haemolymph CO 2 values, suggesting that the animals ‘shuttle’ between air and water, behaviourally influencing internal CO 2 levels. The Leptograpsus exhibited both elevated heart and ventilation rates as well as increased oxygen consumption in water (max. 14.7 μmol · g −1 · h −1) compared to air (6.5 μmol · g −1 · h −1). Part of this increase in rate may be due to increased activity in submerged crabs. The arterial and venous PO 2(86 and 54 torr) and CO 2 (0.52 and 0.31 mmol · l −1) were unchanged by immersion. Re-emersion promoted a transient increase in venous haemolymph oxygenation with respect to the values after 2 h breathing air but not the initial value. The haemocyanin bound O 2, i.e. saturation, was also largely unchanged during immersion cf. air-breathing, which seems to be achieved not by modulation of the haemocyanin functioning but rather by maintaining a constant haemolymph environment. While immersion seems to increase respiratory demand, possibly via increased activity, this does not challenge respiratory gas exchange or transport. In contrast to species reported to date, Leptograpsus maintains extremely high PO 2 in both air and water. Further study of this truly amphibious crab may reveal more as to important intermediate conditions in the transition from water to life on land via the intertidal and supratidal habitats.

A transpacific hydrographic section along latitude 24°N: the distribution of properties in the subtropical gyre

An intensively sampled transpacific hydrographic section along 24°N was completed in the spring of 1985. The data are described here in terms of the spatial distribution of properties, the distribution along isopycnal surfaces, and, where possible, the relationship of these distributions to the large-scale circulation of the Pacific Ocean. Near-surface waters of subtropical origin display a salinity maximum in mid-ocean, with lower salinity to the west due to greater rainfall and lower salinity in the east due to advection of water from the north. In the next layers down, containing waters of subpolar origin, the low salinity and high dissolved oxygen concentrations of those waters are most pronounced in the eastern ocean where the subpolar water is swept clockwise into the subtropical gyre. Differences between patterns of dissolved oxygen concentration and salinity indicate that both horizontal advection and upwelling contribute to observed distributions near the eastern boundary and that the two tracers contain independent information. In the upper kilometer, the eastern Pacific is richer in tracer signals and has steeper property gradients than the west.The deep Pacific has long been recognized to be the most uniform of the oceans. Although property gradients are small, they are significant, and it is found that on all isopycnal surfaces below the upper kilometer salinity increases and dissolved oxygen concentration decreases towards the east on basin-wide scales. These zonal gradients are weakest in the abyss, where there is a substantial net input of southern water, and strongest at mid-depth. Vertical diffusion is the likely cause of the uniformity in this pattern over so much of the deep North Pacific, with oxygen consumption in waters of greater age in the east also being a plausible contributor.With a highly sampled data set such as the 24°N transpacific section it is appropriate to ask how many stations are required to define property distributions and to estimate large-scale circulation and transport. Estimation of geostrophic transport requires high spatial resolution to detect flow near sloping topography at all depths. A 50% decimation of the 24°N station pattern yields a severe degradation in the estimation of transport.

Aquatic and aerial respiration of crassostrea rhizophorae

1. I. Rates of oxygen consumption in water (.VO 2w) and air (.VO 2A) were determined for the mangrove oyster Crassostrea rhizophorae. 2. 2. The ratio of aerial: aquatic .VO 2 (.VO 2A: .VO 2W) was 0.43, suggesting relatively high aerobicity during the first 2 hr of aerial exposure. 3. 3. Air-gaping facilitates .VO 2A and the degree of valve gape is proportional to .VO 2 in air and water. 4. 4. Previous studies indicating high survival rates in air are likely to be accounted for, in part, by aerial oxygen consumption and not an overt resistance to hypoxia or asphyxia.

Effects of Ambient Oxygen Tension and Temperature on the Bimodal Respiration of an Air-Breathing Teleost, Channa maculata

Bimodal oxygen consumption of Channa maculata was measured at 15 C and 25 C in water of different oxygen tensions (Pwo2). In normoxic water (Pwo2 = 130 mmHg), aerial respiration accounted for 34% of the total oxygen consumption (V̇o2) at 15 C and for 60% at 25 C. No significant difference between water oxygen consumption (V̇wo2) at 15 C and 25 C was found. The Q10 value of the total V̇o2 was 2.3. During exposure to hypoxic water (Pwo2 ⩽ 30 mmHg), V̇wo2 decreased while aerial oxygen consumption (V̇ao2) increased, so that the total V̇o2 remained nearly constant at both 15 C and 25 C. At both temperatures, the frequency of aerial ventilation also increased with decreasing Pwo2. However, the amount of oxygen uptake per aerial ventilatory cycle decreased in hypoxic water at 25 C but remained unchanged at 15 C. It appeared that the maximum aerial oxygen consumption in hypoxic water at 25 C was limited by the rate of oxygen absorption in the air-breathing organ. Channa maculata decreased its gill ventilation frequency in response to hypoxic water. However, it continued to extract oxygen from water even when Pwo2 was 20 mmHg. This study showed that the relative contribution of aerial versus aquatic respiration to the total oxygen uptake in C. maculata was altered by changes in ambient temperature and oxygen tension.

Effects of submersion on the oxygen consumption of the estuarine sandhopper Transorchestia Chiliensis (Milne Edwards, 1840)

Oxygen consumption of Transorchestia chiliensis (Milne Edwards) was measured in air and following submersion in sea water of salinity 34%.. In all experimental conditions oxygen consumption increased with dry body weight; the weight exponent in air was 0.76 ( sd ± 0.16) and 0.63 ( sd ± 0.08) in aquatic conditions. At exposure temperatures > 10°C, aquatic rates were consistently below the aerial rate of oxygen consumption, which increased with temperature up to 20°C in winter amphipods and up to 25°C in summer samples. Following submergence, winter-collected amphipods showed maximal oxygen consumption at 10° C and lower oxygen uptake at15°C than at 5°C. For summer amphipods seasonal adjustment in the slope of the R-T curve for aquatic respiration resulted in a plateau of temperature-independent metabolism at temperatures between 5 and 20°C. Oxygen consumption of winter- and summer-collected Transorchestia stored at a constant temperature of 15°C showed a similar relationship between size and oxygen uptake to seasonally collected amphipods. In all acclimated amphipods the oxygen consumption in water remained markedly temperature-dependent up to an exposure temperature of 25°C. Although aerial oxygen consumption of winter-acclimated amphipods approximated the summer values, storage at constant temperatures could not effect completely the changes observed in the aquatic oxygen consumption of seasonally collected amphipods. The ability of Transorchestia to maintain its oxygen uptake at various temperatures following submergence is discussed in relation to the submersion tolerance and its position as a semi-terrestrial member of the supralittoral fringe of New Zealand shores.

The physiological ecology of Mytilus californianus Conrad : 2. Adaptations to low oxygen tension and air exposure.

Mytilus californianus regulated its rate of oxygen consumption (VO2) during decline in oxygen tension, but did not acclimate VO2 when held at 58 mm Hg PO2. In spite of a capacity to consume oxygen while exposed to air (the average VO2 in air being equivalent to 0.74xthe standard rate of oxygen consumption in water), these mussels acquired an "oxygen debt" during aerial exposure which was discharged on subsequent reimmersion. During exposure to air the oxygen tension of the fluid in the mantle cavity was rapdly reduced to approximately 40 mm Hg, in animals both in the laboratory and on the shore. Heart rate was also reduced during air exposure, though not to the point of cardiac arrest. The concentration of ammonia in the fluid of the mantle cavity increased during aerial exposure, but the rate of excretion of ammonia was much lower than during immersion. Observations of mussels on the shore at low tide indicated that dehydration of the tissues was not a serious threat, possibly due to the large volume of fluid retained in the mantle cavity. During aerial exposure some end-products of anaerobic metabolism (alanine and malate) accumulated in the posterior adductor muscle. Malate accumulation was rapid during the first hour of exposure; alanine accumulated more gradually. It is concluded that during aerial exposure M. californianus resorts to anaerobiosis in spite of a capacity to extract some oxygen from the atmosphere. This results in a metabolic deficit during each period of low tide which, coupled with the reduced time available for feeding, imposes a physiological stress on mussels distributed on the shore.

Oxygen minimum laye: vertical distribution and respiration of the mysid Gnathophausia ingens.

The large mysid crustacean Gnathophausia ingens (between 35 and 125 millimeters long) lives at oxygen concentrations between 1.25 and 0.20 milliliter per liter along the coast of California. It lives aerobically at these low oxygen concentrations by regulating its rate of oxygen consumption in water having down to and below 0.26 milliliter of oxygen per liter.

On the vertical distribution of the dissolved oxygen in the ocean

Assuming that about 90 per cent of the oxygen consumption in sea water can be attributed to the oxidation of organic carbon to carbon dioxide, the amount of carbon dioxide calculated from the oxygen consumption ( ΔC) was subtracted from the total amount of carbon dioxide present at two stations in the north-east Pacific. Upon dividing the remainder by the chlorosity, a nearly constant value was found from the surface to about 2,000 metres, giving weight to the validity of the assumption. Seasonal variations in the integrated oxygen consumption in the water column to 1,000 metres were then compared with similar variations in the volumes of plankton taken from the upper 100 metres at two stations in the western Pacific. These values were found to vary similarly throughout the year. These results, and the observations of other authors that the oxygen minimum occurs at nearly the same density in much of the ocean, lead to the conclusion that local productivity and the vertical distribution of density are important factors in determining the vertical distribution of dissolved oxygen and in accounting for the occurence of minimum oxygen concentrations at intermediate depths.

Studies of "Excess-Moisture Injury" in Rape Plants : On the Varietal Difference in Oxygen Consumption

1. Experiments wer conducted to know about the varietal difference in the resistance of rape plants to excess-moisture injury. 2. Three varieties, Namely Norin-15, Norin-16 and Norin-3, were used. as materials. Three hundred seedlings of each variety, very young and their cotyledons, just having opened, were transplanted into four vessels covered with water, and their oxygen consumption in water was measured with Winkler's method. 3. a) The oxygen consumption in Norin-15 was higer than in Norin-16 in the earlier period of submergence while in the later perid the consumption in the latter became higher steadily till, at last, the relation became inverse. (See to Fig. 1) b) Consumption in the roots alone indicated the similar tendency as mentioned above, but the the procession of consumption was prolonged in both the two varieties (Fig. 3) c) When oxygen dissoled in water was scanty, the point where the oxygen consumption became equal between the two varieties was reached ealier than in the case a, and oxygen was consumed rapidly. (See to Fig. 4) d) The uptake of water by the tissues of cotyledons proceeded as shown in Fig 2, namely the quantity of mater uptaken in Norin-15 was the largest of the three varieties. e) Norin-3 was the next to Norin-15 in the intensity of water uptake. 4. Form the results mentioned above, it is clear that there is a difference in oxygen consumption between Norin-16 and Norin-15. According to general idea that the respiration in varieties sensitive against excess-moisture injury would be more active than in resistive ones, Norin-16 may be more resistive than Norin-15. Only a later stage of submergence treatment, the respiration of Norin-15 decreased because of the weakning of plants, and accordingly the resistance of the variety to excess-moisture injury was stronger. 5. We shall consider the respiration of plants of normal growth and the oxygen consumption abnormal growth under oxygen deficiency. 6. Any reasonable relation is found in gas metabolism of plants would not be explained without regulation of the environmental conditions under which they grow.

Metabolic changes associated with pigmentary effector activity and pituitary removal in Xenopus lævis —I. Respiratory exchange

There are various indications of connection between the pituitary gland and basal metabolism; between the pituitary gland and ovarian activity; and between ovarian activity and calcium metabolism. Progress in the study of the relationship of the pituitary to metabolism had been held back by the technical difficulties of mammalian hypophysectomy. By a method described by Hogben, the removal of the pituitary gland as a whole or of the anterior lobe alone can be performed without great difficulty and with great rapidity in adult Amphibia. The animals survive the operation indefinitely. The same author has shown that the posterior lobe of the pituitary gland plays a predominent rôle in controlling colour change, and latterly, in collaboration with Slome, has given strong indications that the anaterior lobe of the gland also plays a part in determining the pigmentary effector activity of the South African clawed toad, Xenopus lævis (Daudin). These circumstances have suggested the advisability of parallel investigation of the effects of the total or partial removal of the pituitary gland and the influence of normal agencies affecting colour change (and thereby pituitary activity) upon the metabolism of this species. The present communication is connected with two issues:— 1. Total respiratory exchange in air. 2. Dermal oxygen consumption in water. The conditions affecting colour response, and the time relations of colour response, etc., in Xenopus lævis , have been recorded thoroughly (Slome and Hogben). These authors have shown that photic stimuli are the predominant natural agencies, the condition for pallor being that the field of vision is occupied by a light-scattering surface, and the condition for darkening that the field of vision is occupied by a light-absorbing surface. Eyeless animals are intermediate in hue but the condition of eyeless animals or animals kept in the dark has been shown to be physiologically different from intermediat animals in a stage of transition from the white background to the black blackground response and vice versa . This conclusion, based on an analysis of the time curve, receives some confirmation from the data hereafter recorded.