Excerpt from The Early Embryology of the Chick
The fact that most courses in vertebrate embryology deal to a greater or lesser extent with the chick seems to warrant the treatment of its development in a book designed primarily for the beginning student. To a student beginning the study of embryology the very abundance of information available in the literature of the subject is confusing and discouraging. He is unable to cull the essentials and fit them together in their proper relationships and is likely to become hopelessly lost in a maze of details. This book was written in an effort to set forth for him in brief and simple form the early embryology of the chick. It does not purport to treat the subject from the comparative view point, nor to be a reference work. If it helps the student to grasp the structure of the embryos, and the sequence and significance of the processes he encounters in his work on the chick, and thereby conserves the time of the instructor for interpretation of the broader principles of embryology it will have served the purpose for which it was written.
In preparing the text, details have been largely omitted and controverted points avoided for the sake of clarity in outlining fundamental processes. While I would gladly have avoided the matters of cleavage and germ layer formation in birds, a brief description of them seemed necessary. Without some interpretation of the initial phases of development, the student has no logical basis for his study of the already considerably developed embryos with which his laboratory work begins. The treatment which it is desirable to accord to gametogenesis and maturation as processes leading toward fertilization would vary so greatly in extent and view point in different courses that it seemed inadvisable to attempt any general discussion of these phenomena.
The account of development has not been carried beyond the first four days of incubation. In this period the body of the embryo is laid down and the organ systems are established. Courses in general embryology rarely carry work on the chick beyond this phase of development.
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