The appearance of the extensive cumulative index at last permits the work to be used to the full, as in the past a thorough knowledge of enzyme chemistry was sometimes needed to find one's way through the haphazardly classified material. The index contains several references to compounds which appear in the text under different names and the reader is expected to know that he will have to consult "adenylic acid" for full information about AMP after studying "adenosine monophosphate" and "adenosine phosphate". The coenzyme of numerous dehydrogenases is found both under "NAD" and "DPN". Once again two camps - the adherents to modern and to old nomenclatureare found in a book where uniformity is so desirable. Finally, depending on whether the contributions happen to be English or German, there are references to the same enzyme as e.g. "pancreatic carboxypeptidase" and "pancreas carboxypeptidase". Surprisingly, the action of amethopterin (and the same holds for aminopterin) on deoxyribonuclease is recorded, but not the much more significant action on the folic aciddependent enzymes (e.g. Part B, p. 196). The contents of the third part are assembled in a similar way to those of the first two. In some instances literature references extending to very recent times are included, in others (e.g. aconitase, carboanhydrase, thiamine pyrophosphate-containing enzymes) only those to the end of the fifties. Both encyclopedic articles and short contributions restricted to descriptions of methods are found side by side. The absence of an article on catalases or peroxidases is regrettable. Handbooks such as this quickly become dated, especially, if some of the contributions are already out of date on the day of publication. Will it be wise to bring out a new edition soon? The reviewer thinks not, unless the structure of the handbook is fundamentally altered. Articles more than 100 pages in length will make it increasingly difficult to find qualified authors who will deliver on time manuscripts incorporating the latest advances. A large number of short articles would surely be entirely adequate for a book of enzyme methods. The editors would then have to coordinate the contributions and edit them systematically. The "Methods in Enzymology" should serve as a model. If each enzyme were treated by one author, it would be possible to go one step further in a future edition to keep the handbook abreast of new developments. Law books have for some time been issued in the form of loose-leaf editions, so that parts can be