Current Therapy 1951

some time. The compilation of a book of this type requires that the author have considerable experience in teaching and close contact with current literature. Since Rugh has been active in research and teaching of experimental embryology for some years, it was anticipated that he would produce a text that would be satisfactory to both student and instructor. The author opens with an historical background of the study of embryology. There follow sections on the reproductive system of the adult, cleavage, blastulation, gastrulation, early organogeny, and the germ layer derivatives. The general organization and physical makeup of the book are excellent. The illustrations are perhaps the finest to appear in a text on this general subject, although the convention of numbering illustrations was ignored in spite of its pedagogical usefulness. No account of early amphibian embryology can be considered complete without reference to data obtained by experimental methods. It is in the presentation and interpretation of the experimental work of others that the author is least effective. It is disappointing to find perpetuated without discussion certain concepts of the mechanisms and processes of embryonic development which have been rendered doubtful or refuted by investigations of none-to-recent date. Thus the roof and walls of the archenteron are represented as originating by delamination from material which has passed over the dorsal lip of the blastopore without reference to the conflicting experimental evidence obtained by Vogt twenty-two years ago. Personal opinion, information backed by experimental evidence, and hypothesis are often presented without identification. The result is confusing. Subsequent sections dealing with later descriptive embryology are considerably improved, being well organized and illustrated. However, this description, like the rest of the book, suffers from lack of documentation, thus denying the interested student rapid access to the literature on a particular subject. In general, the text frequently appears to have been written in haste and reread in the same manner. There are pronouns with doubtful antecedents, sequences of events are described in such a way as to leave the order in doubt, and not infrequently the construction of sentences and paragraphs is so awkward that many rereadings are necessary before one can grasp what the author is trying to express. An example may be found on page 170 where four consecutive sentences begin with the word "this." On the whole, it may be said that in spite of the excellence of the illustrations this is …