. The biology of the amphibia. Amphibians. THE RESPIRATORY SYSTEM 165 exposed would dry due to the absence of glands and would soon lose their respiratory function. The respiratory organs of terres- trial vertebrates are the lungs. These arose in phylogeny long before the land was invaded. They are found today in both dipnoans and crossopterygians, and it seems probable that crossopterygian fish closely allied to the ancestors of Amphibia. Fig. 64.—Frontal section of a larva of the midwife toad, Alytes, showing the resemblance of the lung rudiments to branchial pouches. , lung anlagen. Vis
. The biology of the amphibia. Amphibians. THE RESPIRATORY SYSTEM 165 exposed would dry due to the absence of glands and would soon lose their respiratory function. The respiratory organs of terres- trial vertebrates are the lungs. These arose in phylogeny long before the land was invaded. They are found today in both dipnoans and crossopterygians, and it seems probable that crossopterygian fish closely allied to the ancestors of Amphibia. Fig. 64.—Frontal section of a larva of the midwife toad, Alytes, showing the resemblance of the lung rudiments to branchial pouches. , lung anlagen. Visceral pouches numbered. {After Makuschok.) had paired air sacs of the same form as lungs (Barrell, 1916). Further, both air bladders and lungs arise from entodermal pockets of the pharynx which are serially homologous to the pockets which break through to form the gill clefts. That lungs are branchial pouches and not mere intestinal diverticula which have taken over secondarily a respiratory function is well shown by their development (Fig. 64) in the more primitive Amphibia and especially by the Gymnophiona as described by Marcus. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Noble, Gladwyn Kingsley, 1894-1940. New York : McGraw-Hill
Size: 1266px × 1973px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookpublishernewyorkmcgr, booksubjectamphibians
