Book - The Early Embryology of the Chick

Preface

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. More extensive courses in which a knowledge of mammalian embryology is the objective, ordinarily pass from the study of three or four day chicks to work on mammalian embryos.

While the text has been kept brief, illustrations have been freely used in the belief that they convey ideas more readily and more accurately than can be done in writing. Direct labeling has been used in the figures to facilitate reference to them. Most of the drawings were made directly from preparations in the laboratory of Histology and Embryology of Western Reserve University School of Medicine. However, figures from other authors, particularly Lillie and Duval, have been used extensively for comparisons and for schemes of presentation. Several figures have been reproduced directly or with only slight modifications. These are designated in the figure legends.

I wish to acknowledge the assistance I received in the preparation of material by Mrs. Mary V. Bayes, and in the drawing of the figures by Mrs. Bayes and Dr. Louis J. Karnosh. I am "also indebted to my father, Prof. Wm. Patten of Dartmouth College for criticism of the figures, and to Dr. F. C. Waite of the School of Medicine, Western Reserve University for his helpful interest and cooperation in all phases of the preparation of the book and especially for his reading of the manuscript.

Bradley M. Patten. Western Reserve University, School of Medicine. Cleveland, Ohio.

Online Editor Comments

If like me you are interested in development, then these historic embryology textbooks are fascinating in the detail and interpretation of embryology at that given point in time. As with all historic texts, terminology and developmental descriptions may differ from our current understanding. There may also be errors in transcription or interpretation from the original text. Currently only the text and early chicken images have been made available online, later figures will be added at a later date. My thanks to the Internet Archive for making the original scanned book available. --Mark Hill 13:24, 14 January 2011 (EST)