Certain So-called Malpositions a Natural Occurrence in the Normal Development of the Chick Embryo

Abstract

IT has been demonstrated repeatedly that many chick embryos dying on the eighteenth day of incubation or later and examined generally on the twenty-second day are not in the normal position for hatching. This study offers additional information with reference to the position of the embryo within the egg after the eighteenth day of incubation. The evidence presented indicates that certain of the previously designated malpositions found in chick embryos are but a natural stage in normal development.In an admirable treatise Kuo (1932b) states that “the chick has been the favorite subject for embryological investigation for more than one hundred years.” It might be added that embryologists have given most of their attention to the early stages rather than to all stages of chick development. From the economic point of view we are equally concerned with all stages of development, for any deviation from normal may decrease the hatchability .