. The Bible and science. ungs become all undergo a metamorphosis after leaving theegg. In their young state they are always more fish-like, and this resemblance becomes less as they growolder. Their limbs are never developed into fins, as infishes, and their gills are generally external, placedoutside the neck, instead of being situated in a cavity,as in the fishes. We have already mentioned, however, that in themud-fish we have both kinds of gills present, andthe same is the case in the early condition of frogs andtoads, both of which have external and internal gills,and the ex
. The Bible and science. ungs become all undergo a metamorphosis after leaving theegg. In their young state they are always more fish-like, and this resemblance becomes less as they growolder. Their limbs are never developed into fins, as infishes, and their gills are generally external, placedoutside the neck, instead of being situated in a cavity,as in the fishes. We have already mentioned, however, that in themud-fish we have both kinds of gills present, andthe same is the case in the early condition of frogs andtoads, both of which have external and internal gills,and the external disappear first. The nasal sacs always open into the mouth, andthere is a common cloaca, into which the intestine,kidneys, and reproductive organs all empty the early part of the life of an amphibian, itscirculation resembles that of a fish, there being onlytwo chambers to the heart, but, as the animal deve-lops, a third chamber appears, and then the condition PROTEUS AND AXOLOTL. 191 — ^ ?So. 192 METAMORPHOSES OF AMPHIBIA. is like that which we find permanently in the ordernext above the amphibia, viz., the reptiles.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectnaturalhistory, booky
