A Manual of Embryology

validity to all older obcervations of high or low blood iodine. The situation is even more hopeless when the attempts to separate blood iodine into organic aiid inorganic fractions are considered. Separation of fractions by methods of doubtful chemical validity have been combined with inaccurate methods for the determination of iodine. Until all these observations dealing with fractions of the blood 'iodine have been repeated using satisfactory methods, no conclusions can properly be reached. Chapters are included dealing with the relation of the thyroid to the "pituitary-ovarian axis," with neurological influence, and with radioactive iodine as a tracer substance. Much valuable material bearing directly on clinical matters is scattered throughout the text, and the final chapter deals specifically with clinical problems. There is an appendix dealing with chemical methods, and an exhaustive bibliography covering the entire subject. Anyone whose work touches on the problems of thyroid function will find in this volume a wealth of thought-provoking material. The book should, in fact, appeal to any serious student of endocrine problems. Its value to the biochemist is self-evident. This is the first in a projected series of monographs in medicine and public health to be published by the Harvard University Press, under the editorial supervision of a committee of the Harvard Medical School. The scholarly character of the present work sets a high standard of excellence for the series. This manual deals entirely with the development of the human body except that in the first chapter, on development of sex-cells, etc., it must necessarily depend upon lower forms. The book has been exceedingly popular in England and is now used there as practically the authority in embryology. In comparison with our own textbooks readily available here, it is inferior to Arey in both style and illustrations as well as in the general descriptive material. It follows the old classical morphological lines, and takes into account none of the experimental work which has been done either on mammals or other vertebrates in an attempt to explain the causative factors underlying development. It contains very little of an outside viewpoint beyond what would be derived from a study of the embryology of the last century. Because the human is considered very much by itself one finds striking contrasts between this and other mammals as well as other vertebrates. The section on the development of the nervous system is probably the best part of …