Inaugural dissertation on the nature of respiration, and the extent of its connection with the nervous system : submitted to the Medical Faculty of the University of Edinburgh ... / by George A.F. Wilks.

Date:
1835
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Licence: Public Domain Mark

Credit: Inaugural dissertation on the nature of respiration, and the extent of its connection with the nervous system : submitted to the Medical Faculty of the University of Edinburgh ... / by George A.F. Wilks. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    families. Others, as the “ aphrodita aculeata,” have but one large respiratory cavity, with which the external open- ings are all found communicating. In the class “ Crusta- cea,” respiration is always branchial. The gills are at- tached generally to some part of their articulated feet, their form and situation varying respectively in every order of the class, as in the crab, wood-louse, monoculus, &c. The circulation is double, with a great dorsal vessel, and a true branchial ventricle. In the “ arachnidae,” respiration may be either pulmonary or tracheal, and this has given rise to two grand orders, into which this class has been divided. In both orders, the stigmata or breathing holes are placed beneath the abdomen, but in the one they terminate in saccular organs, with the parietes of which a laminated* respiratory apparatus is connected, and to which the blood is conveyed by a dorsal vessel; in the other, the stigmata ter- minate in “ tracheae,” or air-tubes, which send ramifications to all parts of the body. Spiders, scorpions, &e. are examples of pulmonary arachnidae. The animals called false scorpions, furnish an example of those whose respiration is tracheal. The “ insecta” breathe universally by tracheae. They are furnished with a large dorsal vessel, extending the whole length of the body, through which the blood flows uniform- ly in one direction. This fact, for which we are indebted to the investigations of Professor Carus, is at length esta- blished beyond the possibility of a doubt. From these re- searches it appears, that the streams of blood which permeate the body of the insect, enter the dorsal vessel at the poste- rior extremity, and pass out of it anteriorly. The existence of valves in this vessel tends to corroborate still further the truth of this assertion. The insect tribe presents us with a * It is the laminated structure of the lining membrane of these pulmonary cavities which has procured for them the very inappropriate appellation of “ Pneumobranchuc.