. An introduction to zoology [microform] : for the use of high schools. Zoology; Zoologie. HIGH SCHOOL ZOOLOGY. 43 56. As we shall see hereafter, the air-bladder in some fishes is so well supplied with blood, and communicates so freely with the u3sophagus that it can act as a breathing organ. Such is obviously not its function in the catfish. Again there are fishes which live in deep water, and can by altering the amount of air in the air-bladder, accommodate their specific gravity to that of the water at any particular level. But such an hydrostatic arrangement must be of less service to a ca
. An introduction to zoology [microform] : for the use of high schools. Zoology; Zoologie. HIGH SCHOOL ZOOLOGY. 43 56. As we shall see hereafter, the air-bladder in some fishes is so well supplied with blood, and communicates so freely with the u3sophagus that it can act as a breathing organ. Such is obviously not its function in the catfish. Again there are fishes which live in deep water, and can by altering the amount of air in the air-bladder, accommodate their specific gravity to that of the water at any particular level. But such an hydrostatic arrangement must be of less service to a catfish than to many other groups. The connection with the ear renders it likely that the functions discharged by the air-bladder are of a complex character, but they are not yet well understood. 56. Respiratory System.—We have already studied the skeleton of the gill- arches ; there remain to be examined the soft parts which clothe these. "Within the cavity of the mouth there may l>e observed certain tubercles which fit into each other when the gill clefts are closed, these are the gill-rakers ; they are sometimes of con- siderable size in other fishes, and may act as strainers of the water which flows out through the clefts, over the gills. On the convex side are the gill-filaments, disposed in two rows. (Fig. 17). 51. The vessels which supply the gill- filaments ascend the arches in a groove, which is easily seen on their convex side in Fig. 17—Diagrammatic Sec- /. tion of Gill-arch. the dry condition. Of the four arches, the artery ;"aa)'afferent artery: l^s* is decidedly the shortest, and the same "' "^'^'®- ' is true of the slit behind it. All the slits open freely into the branchial cavity, and this by a very wide aperture to tlfe outside, the apertures of the right and left sides being only separated from each other below by a narrow isth-. '.• V- . J. Please note that these images are extracted from scanned page images that may have been dig
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectzoology
