This book, with its appendix of brief biographies of men commemorated in biological nomenclature, has gone through three editions and five printings since 1944—the last, a full revision with insertion of an addendum. This is remarkable. Clearly, people want to know why things are named as they are. Apparently the sources indicated in medical, biological, and standard dictionaries do not satisfy this need. A further reason for the popularity of the book may be the fallen state of Greek and Latin learning in these decadent, mechanistic, modern times. Whatever the reason, the book has evoked interest which this reviewer shares. The system of arrangement, the orderly explanation of Greek and Latin usage in nomenclature, and the cross references add much to its value. It is aimed at biology generally; hence, many medical terms are not included, although the roots of these can usually be found easily. Thus, it is useful