The Dental cosmos . Fig. Tortoise. Man. Embryos at Fourth Week, showing Gill-Arches (A). exceedingly important formation, of which we are not able to recog-nize a trace in the full-grown animal, are the gill arches, which origi-nally are common to all vertebrate animals, but which at a later period are transformed into the most differentorgans. Everyone knows the gill-arches of fish, those arched boneswhich lie behind one another to thenumber of three or four, on each sideof the neck, and which support thegills, the respiratory organs of thefish. Now, these gill-arches origi-nally exist in emb
The Dental cosmos . Fig. Tortoise. Man. Embryos at Fourth Week, showing Gill-Arches (A). exceedingly important formation, of which we are not able to recog-nize a trace in the full-grown animal, are the gill arches, which origi-nally are common to all vertebrate animals, but which at a later period are transformed into the most differentorgans. Everyone knows the gill-arches of fish, those arched boneswhich lie behind one another to thenumber of three or four, on each sideof the neck, and which support thegills, the respiratory organs of thefish. Now, these gill-arches origi-nally exist in embryo exactly the samein man, in dogs, in fowls, in tortoises,as well as in other vertebrate animals.(See Fig. 1.) It is only in fishes thatthese remain in their original formand develop into respiratory the other vertebrate animals theyare partly employed in the formationof the face (especially the jaw appa-ratus) and partly in the formation of the organ of hearing. An examination of the human embryo in the
Size: 1266px × 1974px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectdentist, bookyear1890
