The Physiology of Excretion in the Cotton Stainer, Dysdercus Fasciatus Signoret

1965 ◽  
Vol 43 (3) ◽  
pp. 511-521
Author(s):  
M. J. BERRIDGE
Keyword(s):  
Water Content ◽  
Large Volume ◽  
Water Loss ◽  
Malpighian Tubules ◽  
Gut Contents ◽  
Osmotic Gradient ◽  
Rapid Rate ◽  
Evaporative Water ◽  
Cotton Stainer ◽  
Two Phases

1. The intestine of Dysdercus is discontinuous in the larval instars, and urine from the Malpighian tubules is therefore uncontaminated by gut contents. 2. Excretion has been studied during the fifth instar, which lasts 8 days. Feeding only occurs in the first 4 days, during which there is a marked fall in water content. In the last part of the instar, when the animal only drinks, the water content returns to its original level. 3. The urine of Dysdercus is always liquid. There is a rapid rate of excretion during the first half of the instar, but when feeding ceases there is no further micturition and urine is retained in the rectum. Therefore there are two phases of excretion, designated excretory and post-excretory phases respectively. 4. The rectal epithelium is incapable of reabsorbing water against an osmotic gradient. 5. The urine which is retained in the rectum during the post-excretory phase acts as a water store; evaporative water loss is balanced by withdrawing water from this reservoir. During the excretory phase, a large volume of liquid is lost via the excretory system, but the loss is made good by drinking.

The Evaporation of Water from Helix Aspersa

1964 ◽  
Vol 41 (4) ◽  
pp. 759-769
Author(s):  
JOHN MACHIN
Keyword(s):  
Water Content ◽  
Water Loss ◽  
Vapour Pressure ◽  
Freezing Point ◽  
Muscular Activity ◽  
Helix Aspersa ◽  
Distilled Water ◽  
Atmospheric Conditions ◽  
Evaporative Water ◽  
Dry Air

1. Observations of intact specimens of Helix aspersa together with experiments with isolated skin preparations are described. 2. Under normal atmospheric conditions increases in haemocoelic pressure, probably due to general muscular activity, are sufficient to maintain the superficial mucous coating of the skin. 3. Under conditions of rapid water loss more intense muscular undulations serve to spread mucus which collects in the grooves to more exposed areas of the skin. 4. The water content, the rate of water loss in dry air, the equilibrium in saturated air and depression of freezing point of isolated mucus samples have been measured. 5. The vapour pressure of mucus has been shown to be within 0.4% of that of distilled water under the same conditions. 6. The significance of the above findings is discussed in relation to evaporative water loss and water uptake of an intact snail.

scholarly journals Hydrophilic Polymers and Wetting Agents Affect Absorption and Evaporative Water Loss

HortScience ◽  
1993 ◽  
Vol 28 (6) ◽  
pp. 633-635 ◽  
Author(s):  
Allyson M. Blodgett ◽  
David J. Beattie ◽  
John W. White ◽  
George C. Elliott
Keyword(s):  
Water Absorption ◽  
Water Content ◽  
Water Loss ◽  
Hydrophilic Polymers ◽  
Wetting Agent ◽  
Hydrophilic Polymer ◽  
Evaporative Water ◽  
Maximum Water ◽  
Maximum Water Content ◽  
Container Capacity

A plantless system using subirrigation was developed to measure water absorption and loss in soilless media amended with hydrophilic polymers, a wetting agent, or combinations of these amendments. Peat-perlite-vermiculite and bark-peat-perlite controls achieved 67% and 52% of container capacity, respectively, after 20 daily irrigation cycles. Maximum water content of amended media was 78% of container capacity. Adding only a hydrophilic polymer did not increase total water content significantly. Adding a wetting agent increased water absorption in both media. However, when hydrophilic polymer and wetting agent were present, the medium absorbed more water than with wetting agent alone. More extractable water was removed from media containing wetting agent. Water loss rate by evaporation was not affected significantly by medium, hydrophilic polymer, wetting agent, or any combination of these variables.

Regional differences in airway surface liquid composition

1981 ◽  
Vol 50 (3) ◽  
pp. 613-620 ◽  
Author(s):  
R. C. Boucher ◽  
M. J. Stutts ◽  
P. A. Bromberg ◽  
J. T. Gatzy
Keyword(s):  
Water Loss ◽  
Regional Differences ◽  
Regional Difference ◽  
Liquid Composition ◽  
Evaporative Water Loss ◽  
Osmotic Gradient ◽  
Airway Surface Liquid ◽  
Evaporative Water ◽  
Surface Liquid ◽  
Electrochemical Equilibrium

Liquid from canine airway surfaces was absorbed onto filter paper strips and analyzed. In resting conditions, tracheal surface liquid was hyperosmolal (330 mosmol/kg H2O) compared to plasma with raised Na+ (158 meq/l), Cl- (134 meq/l), K+ (28 meq/l), and HCO3- (32 meq/l) concentrations. The volume collected was increased by repetitive sampling, a response blocked by atropine, or by methacholine injection. Compared to nose breathing, tracheal surface liquid osmolality was increased by 10 min of mouth breathing (410 mosmol/kg H2O). Surface liquid from 0.5-cm diameter bronchi was nearly isosmolal (304 mosmol/kg H2O) with plasma in resting conditions, with Na and Cl concentrations lower than plasma (120 and 106 meq/l, respectively), and K+ (52 meq/l), and HCO3- (50 meq/l) concentrations higher than those of plasma or tracheal liquid. Although the K+ in tracheal fluid approaches the value for electrochemical equilibrium, K+ in fluid from the bronchi and HCO3- in both regions cannot be accounted for by passive forces. The regional difference in osmolality supports the concept that the higher osmolality of tracheal liquid reflects evaporative water loss from this site. The transepithelial osmotic gradient generated by evaporative water loss may be a driving force for hydration of the tracheal surface.

Evaporative water loss and the role of cocoon formation in Australian frogs

1998 ◽  
Vol 46 (5) ◽  
pp. 405 ◽  
Author(s):  
Philip C. Withers
Keyword(s):  
Water Content ◽  
Water Loss ◽  
High Water ◽  
Linear Increase ◽  
Evaporative Water Loss ◽  
High Water Content ◽  
Evaporative Water ◽  
Wide Range ◽  
Very High

Measurements of evaporative water loss (EWL; mg min-1) and resistance (R; sec cm-1) for various Australian frogs indicate three general allometric patterns: non-cocooned and non-‘waterproof’ frogs with EWL ∝ Mass0.30 and R independent of body mass at about 1–3 sec cm-1, cocooned frogs with EWL reduced about 50–200-fold and R about 50–200 sec cm-1, and ‘waterproof’ frogs with EWL reduced about 5–100- fold and R about 5–100 sec cm-1. Cocooned frogs have an exponential reduction in EWL and fairly linear increase in R over time, corresponding to the temporal addition of layers to the cocoon. The biophysical properties of cocoon are generally similar for various species, although there is some variation in both resistance per thickness (5–20 × 104 s cm-2) and diffusion coefficient (0.4–2.4 × 10 –5 cm2 s-1). The hygroscopic property of frog cocoon resembles that of mammalian stratum corneum, hair and wool, and mucopolysaccharides; there is a slight increase in water content of cocoon over a wide range of humidities but a very steep increase in water content and substantial hydration and swelling at >96% RH. This extreme hygroscopic behaviour of frog cocoon at very high RH may reflect less polymer cross-linking in frog cocoon and its high digestibility. The prevention of over-hydration of frog cocoon in vivo may be attributed to the restriction of high water content to only very high RH (>96%).

Shell Resistance and Evaporative Water Loss from Bird Eggs: Effects of Wind Speed and Egg Size

1981 ◽  
Vol 54 (2) ◽  
pp. 195-202 ◽  
Author(s):  
James R. Spotila ◽  
Christina J. Weinheimer ◽  
Charles V. Paganelli
Keyword(s):  
Wind Speed ◽  
Water Loss ◽  
Egg Size ◽  
Evaporative Water Loss ◽  
Evaporative Water ◽  
Bird Eggs

Scaling of Evaporative Water Loss in Marsupials

1986 ◽  
Vol 59 (1) ◽  
pp. 1-9 ◽  
Author(s):  
David S. Hinds ◽  
Richard E. MacMillen
Keyword(s):  
Water Loss ◽  
Evaporative Water Loss ◽  
Evaporative Water
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