PREEBACH 
Tuts book is a plain account of the development of the never- 
failing resource of the embryologist, the chick. It has been neces- 
sary to fill certain gaps in our knowledge of the development 
of the chick by descriptions of other birds. But the account 
does not go beyond the class Aves, and it applies exclusively 
to the chick except where there is specific statement to the 
contrary. Projected chapters on the integument, muscular sys- 
tem, physiology of development, teratology, and history of the 
subject have been omitted, as the book seemed to be already 
sufficiently long. The account has been written directly from 
the material in almost every part, and it has involved some 
special investigations, particularly on the early development 
undertaken by Doctor Mary Blount and Doctor J. T. Patterson, 
to whom acknowledgments are due for permission to incor- 
porate their results before full publication by the authors. As 
the book is meant for the use of beginners in embryology, refer- 
ences to authors are usually omitted except where the account 
is based directly on the description of a single investigator. A 
fairly full list of original sources is published as an appendix. 
Figures borrowed from other publications are credited in 
the legends to the figures. The majority of the illustrations are 
from original preparations of the author: Figures 46, 48, 50, 51, 
20S, 09;'60,61). 62,63; 64,65, 66, 67.271.-72.0 730 14. 75290: 
105 and 106 were drawn by Mr. K. Hayashi; the remainder of 
the original drawings were executed by Mr. Kenji Toda. The 
photographs in Figures 118, 119, 120, 168, 181, 182, 189, 194, 197, 
and 231 are the work of Mr. Willard C. Green. Some of the 
figures may be studied with advantage for points not described 
in the text. 
Acknowledgments are also due my colleague, Professor W. L. 
Tower for much assistance, and to Doctor Roy L. Moodie for 
special work on the skeleton, and photographs of potash prep- 
arations reproduced in Figures 242, 246, 249 and 250. 
The best introduction to the problems opened up by the study 
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