The Harvey Lectures: Series 69, 1973-1974

cytochemical techniques at the fingertips of electron microscopists. Most available methods, however, are by no means routine, and the neophyte cytochemist is misled by the claim that the books were designed to "enable the worker to prepare his specimens without outside help." Regrettably, Vol. III does not live up to the standard of its predecessors. Nevertheless, numerous gems of advice can be picked from various hiding places. The introductory chapter to Vol. I by Hyat remains obligatory reading. In Vol. III the most lucid chapter by far is that by Higgins and Yates on acetyl coenzyme A carboxylase. This elegant and concise chapter should serve as a prototype outline for future volumes. In fact, the chapter on creatine phosphokinase might become intelligible if reorganized along this outline. Of great promise is the method for purine nucleoside phosphorylase introduced by Rubio. In a generalized form the method should be applicable to the localization of other reversible phosphorylase reactions. In sad contrast, in the design of the presumed method for cellulase a cardinal rule of electron microscopic enzyme methods has been disregarded, i.e., avoidance at all cost of diffusion of the marker reaction product from the site of enzymic activity. As a "control" procedure heat inactivation following the enzyme reaction is pointless. The authors of the two chapters on carbonic anhydrase (why two?) point out the limitations imposed by dealing with a diffusible enzyme and an ill-defined reaction product. The light microscopic localizations are stunning. Critical discussions, especially by Rosen, and some effective electron micrographs, make these chapters worthwhile. Methods for nonspecific esterases are discussed by Shnitka, but the electron micrographs are not convincing. One wonders why the exquisite localizations of Bell and Barrnett were not chosen as illustrations. Instead, the illustrated methods are effective only at the level of light microscopy. The publishers should be advised of the numerous typographical errors that remain in the printed volume and of the omission of an important "and" on p. 57. This volume lacks critical unifying supervision and is of limited practical value, although it is useful for purposes of review.