. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PRINCIPAL AXIS OF SYMMETRY IN THE BIRD S EGG. 351 exceptionally variable. The other three birds laying an aggre- gate of 204 eggs had no inversions. This gives a clue to the reason for the great difference in the number of cases reported for the hen. We are again dealing with a matter of individual variation. It is manifest that we should exclude from our studies involving axis angles all birds which show a tendency to vary over 25° from a mean. How are we to interpret the phenomenon when it does occur? Is it due to an inver
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PRINCIPAL AXIS OF SYMMETRY IN THE BIRD S EGG. 351 exceptionally variable. The other three birds laying an aggre- gate of 204 eggs had no inversions. This gives a clue to the reason for the great difference in the number of cases reported for the hen. We are again dealing with a matter of individual variation. It is manifest that we should exclude from our studies involving axis angles all birds which show a tendency to vary over 25° from a mean. How are we to interpret the phenomenon when it does occur? Is it due to an inversion of relations in the ovary or is it more or less accidental? It is always possible that a normal ovum may be unable to orient itself with reference to gravity before oyula- tion owing to pressure from neighboring ova, adhesions of the. FIG. 4. A diagrammatic polar view of a pigeon's egg showing an "inverted" embryo. This type of inversion can be explained (egg 479' of no. 4). In this particular case the inversion was very probably due to the fact that the end of the long axis of the yolk which should have entered the oviduct first, entered last. oviduct, etc., and so the end of the long axis which should have entered first enters last. It may also have fallen into the ccelom at first and have subsequently entered the duct inverted. Since we have complete records of no. 4 and no. 5, the only birds I ever had which laid inverted eggs there is a basis for something more than speculation. When I opened egg 479' of no. 4 and. 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 Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983.
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
