Document Type



The purpose of this investigation is three-fold: (1) to outline the general embryogeny of the English Sparrow, (2) to determine the relative rates of differentiation of the various external features and (3) to compare the developmental rates of the sparrow with those of the chick and turkey. Two questions arise from the fact that the incubation period of the sparrow is 13 days, while that of the chick is 21 and the turkey 28 days: (1) Is it possible to establish corresponding stages in the three embryos, or do the different organs develop at different times? (2) Are the three at the same stage of development at hatching, or for example, is the sparrow at hatching to be compared to a chick one week before hatching? A series of carefully timed embryos was obtained by incubating fresh sparrow eggs under artificial conditions. Diagnostic features for each day were recorded in chart form so that the age of embryos taken from eggs in nature can be readily determined. An 8 day sparrow embryo is comparable to an 11 day chick or a 14 day turkey embryo in morphological development. However, an adaptive character for hatching, the egg tooth, appears on the 6th day in all three birds.

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Journal Title

Proceedings of the Iowa Academy of Science





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©1941 Iowa Academy of Science, Inc.



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