. The bird, its form and function . FiG. 369.—Pineal eye in Chick (P. E.). The Bird in the Egg 479 ably functional. In an embryo chick of even the thirdday this organ is remarkably prominent; but althoughtraces of it always remain, yet it fades away to a vestige. Look with a hand-lens at the head of a polywog, andsee the whitish dot between the eyes; or when you touch. Fig. 370.—Forty-day embryo Ostrich, showing position in the shell. the ^soft spot on the head of a human baby, let it recallthe strange third eye which is its cause. And so we might continue to tell of the wonder ofembryo life:
. The bird, its form and function . FiG. 369.—Pineal eye in Chick (P. E.). The Bird in the Egg 479 ably functional. In an embryo chick of even the thirdday this organ is remarkably prominent; but althoughtraces of it always remain, yet it fades away to a vestige. Look with a hand-lens at the head of a polywog, andsee the whitish dot between the eyes; or when you touch. Fig. 370.—Forty-day embryo Ostrich, showing position in the shell. the ^soft spot on the head of a human baby, let it recallthe strange third eye which is its cause. And so we might continue to tell of the wonder ofembryo life: how up to the sixth day the little beingmight be mistaken for the embryo of a reptile or a mammai,but from this day onward the bird characteristics becomemore and more noticeable. On the ninth day feathers 480 The Bird begin to be seen, looking, however, more Hke tiny conesthan anything else (Fig. 11). The muscles and the cartilageskeleton are well defined on the fourteenth day, and aboutthis time the tiny beak with its white egg-tooth is pressedagainst the membrane of the air-chamber at the large endof the egg. Reptiles also show this tiny bit of sharp limeupon the head, which drops off soon after its function iscompleted. Not until almost the last day is the mem-brane pierced and the first gasp of air breathed into thelittle lungs. By an instinctive moving
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Keywords: ., bookauthorbeebewil, bookcentury1900, bookdecade1900, bookyear1906
