The Respiratory Mechanisms of Some Insect Eggs

1950 ◽  
Vol s3-91 (16) ◽  
pp. 429-452
Author(s):  
V. B. WIGGLESWORTH ◽  
J.W. L. BEAMENT
Keyword(s):  
Porous Structure ◽  
Outer Layer ◽  
Injection Technique ◽  
Protein Layer ◽  
Insect Eggs ◽  
Quantitative Evidence ◽  
Free Air ◽  
Cobalt Sulphide ◽  
Micropylar Canal

By the use of the cobalt sulphide injection technique the distribution of air in the shell of a number of insect eggs has been studied. Air is usually confined to an inner layer of porous protein, connected with the atmosphere through pores of varying type which are likewise filled with spongy material. In Rhodnius the ‘resistant protein layer’ which lines the shell is the porous structure and the ‘pseudomicropyles’ connect this layer to the exterior. The arrangement in Cimex is similar. In Oncopeltus the spongy walls of the ‘sperm cups’ convey air to a porous inner layer. After laying, the lumen of each cup (the micropylar canal) is occluded with solid cement. In Dixippus the so-called ‘micropyle’ in the ‘scar’ of the egg is the respiratory pore. It is filled with spongy protein containing air and conducts the air to the spongy inner layer of the endochorion. As the egg develops and its contents are reduced in volume, free air collects between the two layers of the endochorion in the region of the pore. In Blattella an elaborate stigmatic apparatus which is moulded in the crista of the oöheca conveys air to a spongy process at the upper pole of the egg and so to a thin porous air-filled layer which lines the chorion. In Bombyx and Ephestia a thin porous inner layer of the chorion containing air communicates with the exterior through scattered pores containing air-filled spongy material. In the eggs of Diptera the chorion consists of tapering columns with spongy walls which unite the cement-covered outer layer to a spongy inner layer containing air. The horns on the Drosophila egg and the dorsal folds on the Calliphora egg provide respiratory outlets for this system. The spaces between the columns contain liquid in Calliphora and Drosophila; in Syrphus these spaces are greatly enlarged and contain air. The spongy layers may become filled with air in eggs which are still bathed in fluid in the oviduct, or in which water is present in adjacent parts of the shell. The mechanism of filling is discussed. In the case of Rhodnius there is quantitative evidence that the system will provide for the respiratory needs of the egg.

Preparation and properties of duplex NI-P-TIO2/NI nanocomposite coatings

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940019 ◽  
Author(s):  
Weihui Zhang ◽  
Di Cao ◽  
Yanxin Qiao ◽  
Yuxin Wang ◽  
Xiang Li ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Wear Resistance ◽  
Corrosion Resistance ◽  
Porous Structure ◽  
Outer Layer ◽  
Nanocomposite Coating ◽  
Nanocomposite Coatings ◽  
Coating Properties ◽  
Duplex Coating ◽  
Plating Solution

Duplex Ni-P-TiO2/Ni coatings were deposited on the brass substrate by using two baths. Ni-P-TiO2 nanocomposite coatings were electroplated as the outer layer on the Ni-plated brass substrate by adding transparent TiO2 sol (0–50 mL/L) into the Ni-P plating solution. The microstructure, mechanical property and corrosion resistance of the duplex Ni-P-TiO2/Ni nanocomposite coatings were systemically investigated. The results show that the interface of duplex coating was uniform and the adhesion between two layers was extremely good. The microhardness of duplex Ni-P-12.5 mL/L TiO2 /Ni coating was [Formula: see text]616 HV[Formula: see text] compared to [Formula: see text]539 HV[Formula: see text] of Ni-P /Ni coating and [Formula: see text]307 HV[Formula: see text] of single Ni coating. Meanwhile, the wear resistance and the corrosion resistance of the duplex nanocomposite coating have also been improved remarkably compared with single Ni coating. However, adding excessive TiO2 sol (more than 12.5 mL/L) caused the agglomeration of TiO2 nanoparticles and led to a porous structure in the outer layer, resulting in the deterioration of coating properties.

Studies on the egg of the horse bot-fly,Gasterophilus intestinalis(De Geer)

Parasitology ◽  
1961 ◽  
Vol 51 (3-4) ◽  
pp. 385-394 ◽  
Author(s):  
R. J. Tatchell
Keyword(s):  
Vitelline Membrane ◽  
Protein Layer ◽  
Inner Membrane ◽  
Free Air ◽  
Air Space ◽  
Bot Fly ◽  
Secondary Layer ◽  
The Subject ◽  
Pore Canals

1. A description is given of the egg ofGasterophilus intestinalis.2. The chorion has been shown to consist of a number of tanned protein and lipoprotein layers.3. The waterproofing of the egg is shown to be dependent on a primary wax layer on the inner membrane of the endochorion and a secondary layer on the vitelline membrane.4. The respiratory requirements of the egg are supplied from a free-air space between the inner membrane and the tanned protein layer of the endochorion which communicates with the atmosphere by specialized pore canals opening into the follicular grooves.Thanks are due to Dr P. Tate for suggesting the subject of this work and for his advice and encouragement during its progress.

scholarly journals The Evaporation of Water from Spiders

1952 ◽  
Vol 29 (4) ◽  
pp. 571-582
Author(s):  
M. E. DAVIES ◽  
E. B. EDNEY
Keyword(s):  
Critical Temperature ◽  
Effect Of Temperature ◽  
Injection Technique ◽  
Total Water ◽  
Critical Temperatures ◽  
Cobalt Sulphide ◽  
Inert Dust ◽  
Indigo Blue ◽  
Rate Of Evaporation ◽  
And Function

1. The purpose of the present work was to investigate and compare the water-retaining properties of the integument in a number of species of spider. Subsidiary investigations concerned the anatomy and function of the ‘tracheae’ as respiratory organs, and the significance of these organs and of the lung-books in total water loss. 2. The anatomy of the tracheae was investigated by means of the cobalt-sulphide injection technique. In Lycosa amentata they consist of four unbranched tubes, and their surface area is approximately one-thirtieth of that of the lung-book leaflets. Injection of reduced indigo blue demonstrates that O2 enters via these tracheae, but the amount is too small to be measured by a standard Warburg manometer, and is insufficient to keep the animal alive if the lung-books are blocked. At 30° C. intact spiders absorb approximately 0.6µl./mg./hr. 3. If the lung-book spiracles are kept open by exposing living spiders to 10% CO2 in air, evaporation increases by nearly 50% (from 16 to 23% of body weight in 24 hr.). There is no significant increase if dead spiders are exposed, possibly because the spiracles do not open. 4. The rate of evaporation into dry air moving at ca. 5.0 cm./sec. was measured from dead and living Lycosa with the spiracles either blocked or free. The spiders were exposed for 15 min. at 10°C. intervals from 10 to 60°C. Up to 30°C. the rates in mg./cm3./hr. were low, never more than 1.6 (dead spiders with free spiracles) and usually <0.6. The rate increases rapidly above 40° C., and at higher temperatures, although differences are small, evaporation is always greater from intact than from blocked spiders and greater from dead than from living spiders. Animals exposed at 2° C. intervals from 40 to 50° C. show the beginning of the steep rise at 42° C.--the critical temperature is therefore in this region. 5. Comparable measurements of evaporation from the integument only were made on the following species: Meta segmentata, Tegenaria derhami, Zilla atrica and Z. x-notata. Lung-book spiracles were blocked, only females were used, and the same individuals were exposed at each temperature except for the Zilla spp. As in Lycosa, the rate of evaporation from all these spiders increases abruptly at a critical temperature, and the shape of the curves is similar to that found in insects. 6. The species stand in the following order as regards critical temperatures (lowest to highest): Zilla atrica, Lycosa, Meta, Tegenaria. Zilla x-notata shows a less well-defined critical temperature, and a lower rate of evaporation than any other species at higher temperatures. 7. Abrasion with an inert dust produces an approximately sixfold increase in the rate of evaporation from Lycosa. 8. The above results are compared with similar measurements in other arthropods. Spiders resemble insects and ticks, and differ from isopods and myriapods, so far as the effect of temperature upon evaporation is concerned, and it is suggested that a discrete wax layer is probably present in the spider cuticle. 9. The suggestion that evaporation is resisted by active secretion of the epidermal cells (as in ticks) is put forward to account for somewhat greater rates of evaporation from dead than from living spiders in similar conditions.

Studies of the Portal Venous System by Injection Technique

1951 ◽  
Vol 17 (2) ◽  
pp. 209-223 ◽  
Author(s):  
R.O. Holmes ◽  
W.V. Lovitt
Keyword(s):  
Venous System ◽  
Injection Technique ◽  
Portal Venous System

Extraverts Have Larger Social Network Layers

2011 ◽  
Vol 32 (3) ◽  
pp. 161-169 ◽  
Author(s):  
Thomas V. Pollet ◽  
Sam G. B. Roberts ◽  
Robin I. M. Dunbar
Keyword(s):  
Social Network ◽  
Social Relationships ◽  
Outer Layer ◽  
Network Size ◽  
Emotional Intensity ◽  
Emotional Closeness ◽  
Network Layer ◽  
Network Layers ◽  
Social Network Size

Previous studies showed that extraversion influences social network size. However, it is unclear how extraversion affects the size of different layers of the network, and how extraversion relates to the emotional intensity of social relationships. We examined the relationships between extraversion, network size, and emotional closeness for 117 individuals. The results demonstrated that extraverts had larger networks at every layer (support clique, sympathy group, outer layer). The results were robust and were not attributable to potential confounds such as sex, though they were modest in size (raw correlations between extraversion and size of network layer, .20 < r < .23). However, extraverts were not emotionally closer to individuals in their network, even after controlling for network size. These results highlight the importance of considering not just social network size in relation to personality, but also the quality of relationships with network members.

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