. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine . umes, what can be shown, thoughless readily than in the case of muscle, that all the tissues areconstantly craving, as it were, for this essential oxygen—wellcalled vital air. Respiration may, then, be regarded from a physical andchemical point of view, though in this as in other instances wemust be on our guard against regarding physiological processesas ever purely physical or purely chemical. The respiratoryprocess in the mammal, unlike the frog, consists of an activeand a (largely)
. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine . umes, what can be shown, thoughless readily than in the case of muscle, that all the tissues areconstantly craving, as it were, for this essential oxygen—wellcalled vital air. Respiration may, then, be regarded from a physical andchemical point of view, though in this as in other instances wemust be on our guard against regarding physiological processesas ever purely physical or purely chemical. The respiratoryprocess in the mammal, unlike the frog, consists of an activeand a (largely) passive phase. The air is not pumped into thelungs, but sucked in. So great is the complexity of the lungsin the mammal, that the frogs lung (which may be readilyunderstood by blowing it up by inserting a small pipe in theglottic opening of the animal and then ligaturing the distended TPIE RESPIRATORY SYSTEM. 367 organ) may be compared to a single infundibulum of the mam-malian lung. Assuming that the student is somewhat conversant with thecoarse and fine anatomy of the respiratory organs, we call at-. Fi<i. 2SJ.— Lungs, anterior view (Sappey). 1, upper lobe of left lung; 2, lower lobe; ; 4, notch corresponding to apex of heart; 5. pericardium; (i. upper lobe ofright lung; 7, middle lobe; 8, lower lobe; 9. fissure: 10, fissure; 11, diaphragm;12. anterior mediastinum; 13. thyroid gland; 14. middle cervical aponeurosis; of attachment of mediastinum to pericardium; 1G, 10, seventh ribs; 17, muscles; 18. linea alba. tention to the physiological aspects of some points in theirstructure. The lungs represent a membranous expansion of 368 COMPARATIVE PHYSIOLOGY. great extent, lined with flattened cells and supporting innu-merable capillary blood-vessels. The air is admitted to the com-
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1890
