I t is a pleasure to write a few lines to welcome this labour of Iove. I t is always dangeraus to draw sharp divisions between the interests of different scientists. However, in the present stage of progress in enzymology, there are those who are primarily interested in the molecular mechanisms of the reactions of a few selected enzymes, while others are involved in the grand scheme of the chemical metabolism of cells or whole organisms. Fortunately Dr. Barman has had experience in both the molecular and the metabolic aspects of enzymology. He therefore knows the require­ ments of research workers interested in enzymes from many different points of view. It would be foolish to hope that a handbook of this kind will provide all the information about enzymes which different specialists would wish to find. The author has attempted to help users in the following way. If one Iooks up a particular enzyme one will find all the basic data and a very good Iist of references for more specialized information. Apart from selection of the type of information provided, the author's judgement on the reliability of data is, of course, of critical importance in a handbook. If contradicting published information about some property of an enzyme has to be sorted out, it is often neither possible to teil the whole story nor to give an objective judgement.