. The anatomy of the salamander. Salamanders; Salamanders. 276 THE SALAMANDER excited, or moving, or is fatigued through being handled, the interval becomes much shorter. The complicated movements carried out to effect the filling and emptying of the lungs are as follows. The depression of the mouth- floor is exaggerated and prolonged. The external nares are open during the first part of this act and the air is drawn into the mouth. This process is known as aspiration. Just as the mouth-floor is ap- proaching its lowest point the nares are closed, or nearly so, so that the residue of air is dr
. The anatomy of the salamander. Salamanders; Salamanders. 276 THE SALAMANDER excited, or moving, or is fatigued through being handled, the interval becomes much shorter. The complicated movements carried out to effect the filling and emptying of the lungs are as follows. The depression of the mouth- floor is exaggerated and prolonged. The external nares are open during the first part of this act and the air is drawn into the mouth. This process is known as aspiration. Just as the mouth-floor is ap- proaching its lowest point the nares are closed, or nearly so, so that the residue of air is drawn from the lungs and mixed with the pure air already in the mouth. This process is called expiration. The mouth-floor then rises and, the nares re- maining closed, the mixed air is forced into the lungs. This constitutes the act £)iagram of the ^^ inspiration. The nares then open again respiratory movements of the and there follows a longer or shorter Salamander, comprising the clo- period of bucco-pharyngeal respiration sure of the nares (upper line), the before this more complicated process of rTTracinS'^'n^The'^T P^^^'^^U respiration is repeated. moTrVpreTure\w^ To summarize: it seems that in all (After Willem.) Urodeles devoid of gills, the bucco- I. Commencement of pharynx is the region which is chiefly aspiration. 2. Opening of concerned in the gaseous interchange the glottis and the commence- ^^tween the blood and the air, to which ment of the closure ot the , , • 11 /• 1 r 1 • 1 nares. 3. The nares com- the skm and lungs (m those forms which pletely closed. 4. Closure possess them) are subsidiary. In support of the glottis. 5. Com- of this it should be noted that the whole mencement of the opening of of the mouth and throat is richly vascular, while Bethge has observed that the capil- laries of this region approach very close to the surface, actually pushing into the epithelial layer, between the cells. 2 4 Text-Fig. 3. the nares. 6. completely open. The BIBLIO
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