Trueman e r (18 Ergebnisse)

Zustand: Good. DJ will be clean and have at most light wear. Book will have been read but remains in excellent condition. Clean and tight binding. Cover may show slight wear. Contents will be clean and free from markings.

Zustand: Good. 1st Edition. Former library copy. Pages intact with minimal writing/highlighting. The binding may be loose and creased. Dust jackets/supplements are not included. Includes library markings. Stock photo provided. Product includes identifying sticker. Better World Books: Buy Books. Do Good.…

Softcover. Zustand: Very Good. Zustand des Schutzumschlags: N/A. 1st Edition. viii, 200pp. Pictorial laminated light card covers illustrated throughout with black and white illustrations and photographs. 8vo. Sun-faded covers, light chipping to edges and wear to covers. Text block edges starting to tan. Internally, neat, clean, bright and tight. Presents new material against the background of earlier studies, and shows how soft-bodied animals have been able to move about successfully in a variety of habitats.…

Paper covers. Zustand: V.g. No Jacket. Revised edition. Owner's signature. Weight: 1.0 Language: English.

Society for Experimental Biology, Seminar Series 5. Cambridge University Press. 1980. 250 S. gr.8. m. zahlr. Textabb. Kt.-2)englisch. ISBN: 0521297958.

Donax denticulatus burrows in a similar manner to other infaunal bivalves, but also reacts to stimulation by activity and so proved to be suitable material for experiments on the control of locomotion. Tactile responses of the foot initiate burrowing and pedal stretch receptors control the duration of each digging cycle. Prevention of adduction of the valves, removal of ligament or cardinal hinge teeth, had little effect on burrowing and it is suggested that part of the digging cycle is programmed within the nervous system without peripheral feedback. Experiments on migratory behaviour are discussed and indicate that no intrinsic mechanism is required for its control beyond the adaptation of behavioural responses, common to most bivalves, to different physical conditions. 17 pp., 9 figs, gr. 8.…

Surface locomotion and burrowing by Bullia digitalis have been analysed by use of ciné film and electronic recording. Both movements are shown to be carried out by a series of steps in which the propodium is first extended whilst the snail is anchored by the posterior of the foot (penetration anchor) and, when buried, also by the shell; secondly the shell is drawn forwards and downwards towards the anchored propodium (terminal anchor). The extremely flattened foot of this snail contains a greatly enlarged pedal sinus containing blood and functions as a hydraulic organ. This contrasts with the foot of most gastropods, e.g. Patella, which crawl over hard surfaces and have no large fluid filled pedal cavity. During each step, or digging cycle, there are two pressure pulses, one effecting propodial extension, the second occurring as the shell is drawn forwards. The pedal haemocoel is isolated from the remainder of the circulation for at least part of the locomotory cycle so enabling the foot to function as a fluid-muscle system at constant volume. Bullia exhibits convergence with burrowing bivalve molluscs having a similar pattern of alternating anchorages in sand and in both water is ejected from the mantle cavity to liquefy the sand in front of the shell. The energy cost of burrowing by B. digitalis is estimated to be 6.6 times 10-6 J/mg dry tissue weight, a figure comparable to that of the clam Donax provided that burial occurs at a similar rate. By contrast the energy requirement for Bullia to move over the surface of sand is about one tenth of that for burial. Pedal extension involves both blood flow, so that the foot may function as a hydraulic system, and direct muscular antagonism between the fibres of a three dimensional muscle network in the opercular muscle. When the snail is extended the shell contains some sea-water which plays a dynamic role in pedal expansion and retraction independently of the pedal blood sinus. The possible role of this cavity in other prosobranchs is discussed. 10 pp., 7 figs, gr. 8.…

The pleurembolic proboscis of Bullia functions in the manner of a classical hydrostatic skeleton. Its protrusion occurs both with high pressure pulses (2 KPa) in the cephalic sinus and at a steady standing pressure (0.2 KPa). The proboscis probably functions as a haemocoelic chamber separate from the cephalic sinus and pressure pulses from within the everted proboscis, but not the sinus, suggest that muscle antagonism occurs in a manner common to hydrostatic skeletons. The advantages of the proboscis having a hydrostatic skeleton are discussed. 9 pp., 3 figs, gr. 8.…

Donax serra burrows powerfully and rapidly in the same manner as other infaunal bivalves except that the turgidity of the foot is increased by a standing pressure of up to 3 kPa in the pedal haemocoel. The standing pressure, upon which probing and adduction pulses are superimposed, is derived from muscular tension acting on the blood in the pedal haemocoel, which is held at near constant volume by the closure of Keber's valve. Blood flow through the foot is thus reduced to a minimum at the time of maximal pedal activity and it is possible that pedal respiration is anaerobic during burrowing. Extension of the foot is brought about by blood flow and antagonistic musclc action using blood in the pedal haemocoel as the fluid of a classical fluid-muscle system. There is no evidence of the presence of a muscular antagonistic system causing pedal protraction as occurs in the columellar muscle of some cyrtosome molluscs. 11 pp., 4 figs, gr. 8.…

The cuticle of Proneomenia consists of a mucoid matrix containing calcareous spicules and is secreted by the mantle epithelium at the base of the ventral (pedal) groove and over the general body surface. Histochemical examination shows the matrix to be composed of a glycoprotein complex with high acid mucopolysaccharide and low protein contents in which tanning plays little part in stabilization. The cuticle of the Aplacophora is tentatively equated with an early mucoid stage in the evolution of the molluscan shell and it is suggested that secretion of additional protein, followed by hardening by quinone-tanning, are necessary further stages before a calcified shell evolves. The aplacophoran cuticle is compared with that of Acanthochitona (Polyplacophora) and, although they are similar in many respects, the latter has in addition a discrete inner cuticular layer whichmay act as a semi-conducting membrane in the deposition of the calcareous plates. The spicules are similar in both groups, each being secreted within a thin cup-like membrane which exhibits somewhat similar properties to the inner cuticle. 9 pp., 2 figs, gr. 8.…

The structure and growth of the polyplacophoran shell, characteristically consisting of eight plates surrounded by a girdle, is examined in the light of current views on the relationships of mantle and shell in the Bivalvia. The periostracum and outer and inner calcareous layers of the shell of the latter group are homologous with the cuticle, tegmentum and articulamentum respectively of the shell of the Polyplacophora. The margin of the mantle consists of a large marginal fold, which secretes the cuticular girdle, and a small accessory fold bearing mucous cells. These are functionally comparable with all three folds of the mantle margin found in other molluscs, although anatomically the marginal fold of the chitons probably represents only the inner surface of the outer fold of the mantle margin. The cuticle not only forms the girdle, which bears calcified spines or spicules, but also extends between the shell plates. The principal part of the cuticle consists largely of mucopolysaccharide material but there is also a thin discrete inner region which is similar chemically to the periostracum of other molluscs. The cuticle, possibly without spines, probably covered the entire dorsal surface of a primitive placophoran and beneath this, plates developed. As these grew the cuticle became worn away except marginally and between the plates. It is suggested that a covering of mucus over the visceropallium may have been the forerunner of the molluscan shell and the possibleevolutionary relationships of the shell throughout the Mollusca are discussed. 17 pp., 6 figs, gr. 8.…

Cambridge, 1980. 250 pp. Ills. Softcover. (Society for Experimental Biology, Seminar Series, 5).

Middlesex, England. Penguin Books. 400 pp., num. b/w figs, br. 8.

paperback. Zustand: Befriedigend. 256 Seiten; 9780521297950.4 Gewicht in Gramm: 500.

Hardcover. , several figs & tables, boards 0.0.

Zustand: Good. Your purchase helps support Sri Lankan Children's Charity 'The Rainbow Centre'. Ex-library, so some stamps and wear, but in good overall condition. Our donations to The Rainbow Centre have helped provide an education and a safe haven to hundreds of children who live in appalling conditions.…

Zustand: gut. 1983. Mollusca Volume 12: Paleontology and Neontology of Cephalopods In englischer Sprache. pages.

(USA) 1968, 8vo stralcio con copertina posticcia muta, pp. 401/410 con 4 figure. - !! ATTENZIONE !!: Con il termine estratto (o stralcio) intendiamo riferirci ad un fascicolo contenente un articolo, completo in se, sia che esso sia stato stampato a parte utilizzando la stessa composizione sia che provenga direttamente da una rivista. Le pagine sono indicate come "da/a", ad esempio: 229/231 significa che il testo ?® composto da tre pagine. Quando la rivista di provenienza non viene indicata ? perch? ci ?® sconosciuta. - !! ATTENTION !!: : NOT A BOOK : ?Äúextract?Äù or ?Äúexcerpt?Äù means simply a few pages, original nonetheless, printed in a magazine. Pages are indicated as in "from?Äù ?Äúto", for example: 229/231 means the text comprises three pages (229, 230 and 231). If the magazine that contained the pages is not mentioned, it is because it is unknown to us.…