Energy Changes in Biochemical Reactions

factors in bringing about the development of organ systems in plants and animals. From these presentations, the botanist's and zoologist's position on the degree of reversibility of the differentiated state is found to be quite different. Professors J. A. D. Zeevaart and V. B. Wigglesworth describe the pervasive ontogenic influences exerted by hormones on plants and insects. In addition, the role of nucleo-cytoplasmic interaction in cell differentiation is given much attention. Professor W. Beermann provides an excellent analysis of the structure and function of the chromosome and of the correlation between chromosomal and cellular differentiation. WVhile the scope of this symposium is praiseworthy in its inclusion of many approaches and viewpoints often not found in one volume, it is unfortunate that the individual authors do not relate their work to that of the other participants or comment, in a discussion section, on the lectures presented here. For the above reason, some of the potential value of the book is lost. This volume is to be commended for both the excellence of the individual contributions and their juxtaposition. Those interested in the general problem of cell differentiation would certainly profit from several of the selections.