The philosophy of health; or, An exposition of the physical and mental constitution of man, with a view to the promotion of human longevity and happiness / By Southwood Smith.

  • Smith, Southwood, 1788-1861.
Date:
1836-1837
Catalogue details

Licence: Public Domain Mark

Credit: The philosophy of health; or, An exposition of the physical and mental constitution of man, with a view to the promotion of human longevity and happiness / By Southwood Smith. Source: Wellcome Collection.

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    ]. Respiratory tufts. 2. Artery and vein, supplying the respiratory apparatus. 3. Dorsal vessel. ing annelides, these tufts form a fan-like expan- sion around the head; but at other times they are disposed in regular series along the whole extent of the body. 340. Instead of branchiae in the form of rami- fied tufts, the ascending series of animals, namely, the higher Crustacea, possess branchiae composed of numerous, delicate, thin laminae or leaves, divided from each other, yet placed in close prox- imity, like the teeth of a fine comb, whence this arrangement is termed pectinated. Over the blood-vessels of the system spread out on these delicate, fringed, pectinated leaves, the water is driven in constant streams. 341. Still higher in the scale, as in molluscous animals, an internal sac is formed to which are sometimes attached numerous tufts; but which at other times is itself plaited into beautifully dis- posed regular folds, crowded with blood-vessels and constantly bathed with fresh currents of water. 342. In all these water-breathing creatures, respiration is effected, either by the progressive motion of the body through the water, or by the creation of currents which bring fresh strata of the fluid into contact with the respiratory sur- faces. Both objects are effected by the same in-