. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 580 CETACEA. Fig. Structure of the lung of the Dugong. the pulmonary artery is proportionally smaller. From the difference that exists in the locomo- tive habits of the two animals arising from the difference in the nature of the food, may be deduced the circumstances which relate to the difference in the respiratory organ. The Por- poise, ever bounding and gambolling on the surface, breathes as it were at will; whilst the Dugong is compelled to prolonged submersion in order to acquire its food, which from its fixe
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 580 CETACEA. Fig. Structure of the lung of the Dugong. the pulmonary artery is proportionally smaller. From the difference that exists in the locomo- tive habits of the two animals arising from the difference in the nature of the food, may be deduced the circumstances which relate to the difference in the respiratory organ. The Por- poise, ever bounding and gambolling on the surface, breathes as it were at will; whilst the Dugong is compelled to prolonged submersion in order to acquire its food, which from its fixed attachment, and comparatively innutri- tious nature, necessarily demands much time in collecting.] It is said that, in the Dolphins, each lung is surrounded by muscular fibres, which take part also in the acts of inspiration and expi- ration, and that the lobes communicate with each other in such a manner that, air being introduced through one of the bronchi alone, they are all filled with it. Fig. But though the diaphragm, the lungs, the bronchi, and the trachea are only found with modifications of a secondary order, the nostrils, which serve intermediately for the passage of the air, between the atmosphere and the respiratory organ, present very im- portant ones. It is especially upon these mo- difications that the exterior distinction between the Herbivorous and the Spouting Whales de- pends, [n the structure of the nostrils, the mechanism by which the phenomenon of the spouting is produced has necessarily caused some changes, which, on the one hand, appear to have necessitated the exclusion of the organ of smell, and, on the other, to have led to the formation of a new organ entirely peculiar to this order of Mammalia. We may be allowed to believe that this organ is essentially the same in the Dolphins, the Cachalots, and the Whales; it has only, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readabili
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