The structure, functions, and diseases of the lungs / by Thomas Williams. Part I., Water and air-lungs of invertebrate animals, and aquatic respiration.

  • Williams, Thomas.
Date:
1857
Catalogue details

Licence: Public Domain Mark

Credit: The structure, functions, and diseases of the lungs / by Thomas Williams. Part I., Water and air-lungs of invertebrate animals, and aquatic respiration. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    body (figs. 8, 9, d; fig, 10, *) (i. «. the spacious interval which separates the digestive from the integumentary system] » h led in a// species with a fluid which the author has called the chyl- aqueous: 2nd, the protrusile suctorial feet (PI. XI1. tig. *,ffi fio- 9 f) are occupied by another class of fluid; this system constitutes the water-vascular system of Tiedemann and Mullet•; 3rd, the blood-vascular system (fig. 10, j), of Tiedemann, Delle Chiaje, Valentin, Agassiz, Dr. Sharpey and Miiller : these three systems arc defined as severally distinct and independent, and their functions respectively are alleged to be distinct and inde- pendent. In what conceivable manner is the descriptive anato- mist to depict the breathing systems of these animals, unless by that of first adjusting these long-controverted questions? The ultimate structure of those solid parts, on which the office of aerating the vital fluids is represented to devolve, must be first determined. This inquiry alone can prove to what extent, if at all, these parts are capable of answering the purpose which they are stated to fulfil. The chylaqueous system of fluids exists in every Echinoderm ; the water-vascular system does not exist in every species. In the Sipuncles and the Ophiurida, it has no place. The blood-vascular system is very imperfectly known. Little has been done to demonstrate its presence in the asteroid Echinoderms, and still less in the Echinidse. Its history has been most fully developed in the Holothuridan and Sipunculidan genera. 1. The Chylaqueous System of the Echinoderms. Is it capable of subserving a respiratory purpose ? Is it con- stituted such that it is physiologically capable of executing this great function ? And is it also distributed appropriately ? The mass of fluid occupying the visceral cavity, bounded on one side by the digestive system, on the other by the integuments, has been described, by the classical authorities upon this subject, as consisting purely of sea water, admitted directly from without through the skin, for the exclusive purpose of aerating the blood- proper, said to circulate in a capillary system of vessels wrought in the solid parietes circumscribing the cavity. This, in succinct expression, is the doctrine of the schools, as to the mechanism of respiration in this interesting class of animals. It supposes the existence of a profuse plexus of capillary vessels carrying true- blood, distributed over all the visceral and parietal surfaces limiting the chamber in question. It may be at once stated, that no approach to a demonstration of the presence of this system has ever been made by any modern or ancient anatomist. Is it logical to erect one hypothesis upon another ? Let facts be first represented. In the Asteridse, Echinidse, Ophiuridre and Ophio-