The microscope and its revelations . els (Fig. 331). In this manner, a set of air-cells isFi&. 331. formed in the thick- ness of the upper wallof the lung, whichcommunicates withthe general cavity,and very much in-creases the surfaceover which the bloodcomes into relationwith the air; buteach air-cell has acapillary network ofits own, which lieson one side againstits wall, so as onlyto be exposed tothe air on its freesurface. In the elon-gated lung of the Snake, the same general arrangementprevails; but the cartilaginous reticulation of its upper partprojects much further into the cavity, and
The microscope and its revelations . els (Fig. 331). In this manner, a set of air-cells isFi&. 331. formed in the thick- ness of the upper wallof the lung, whichcommunicates withthe general cavity,and very much in-creases the surfaceover which the bloodcomes into relationwith the air; buteach air-cell has acapillary network ofits own, which lieson one side againstits wall, so as onlyto be exposed tothe air on its freesurface. In the elon-gated lung of the Snake, the same general arrangementprevails; but the cartilaginous reticulation of its upper partprojects much further into the cavity, and encloses in itsmeshes (which are usually square, or nearly so) several layersof air-cells, which communicate, one through another, withthe general cavity.—The structure of the lungs of Birdspresents us with an arrangement of a very different kind, thepurpose of which is to expose a ver^r large amount of capil-lary surface to the influence of the air. The entire mass ofeach may be considered as subdivided into an immense number. Interior of upper part oi Lung of Frog. LUXGS OP EIEDS A^B MA3I3IALS. 737 of lobules or lunglets (Fig. 332), each of wkich has itsown bronchial tube (or subdivision of the windpipe), and itsown system of blood-vessels, which have very little communi-cation with those of other lobules. Each lobule has a central Fig, 332.
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Keywords: ., bookcentury1800, booksubjectmicroscopes, booksubjectmicroscopy
