142 Book Reviews

can propagate efficiently. The confusion in the book arises because any mode may be represented as the sum of two interfering plane waves. But it is important to realise that these waves are essentially plane, and the mode concept is a steady-state or infinite-distance concept. These interfering waves must not be confused, as in the book, with the rays which join source and receiver, such a ray is essentially a finite-distance concept.

The book under review is basically a well-conceived publication filling a real need. But its value in this first edition is greatly reduced by some unfortunate lapses, occurring especially in the sections on propagation.

Admiralty Research Laboratory, D.E. WESTON Teddington

The Living World of the Sea. WILLIAM J. CROMIE, 1966. Prentice-Hall, New Jersey. 343 pp. $6.95.

Tins book was not written for you, a reader of Deep-Sea Research, but if you have a wife or aunt who does not understand why your work means so much more to you than just earning their keep, then you should give them this book. It will help enormously. They will not mind one of the organisms associated with red-tides being ca l l ed" Jim Brevis" or Oikopleura referred to as "Oiky ." If you have an up and coming youth in your family who would like to feel " w i t h i t " about his father's work he will revel in such sentences as " Immorta l ized in literature as ' the mighty Kraken ' this bizarre beast would make many of tbefearsome dinosaursofprehistorylooklikeunderfedalleycats . , , D o n o t be misled by these and similar phrases, the book is packed with a mass of information gleaned by the author from voracious reading of scientific papers, books and reports, from all over the world and put together in a way that passes on his enthusiasm to the reader. It is a whole catalogue of data, yet is not a catalogue but a very readable book and it is all to the good that marine biology can be put across to interested lay readers in a manner that emulates a M_AgOEgY ALLUqQI-L~ story. Though not likely to be read cover to cover, non-stop, in thriller style, this book can be opened at any page, at any time, and it won' t be put down in a hurry. What is more, it is right up-to-date.

The author makes full use of a sense of the dramatic, and can you blame him if, to do this, he commits some sins o f commission and some sins of omission ? Concerning Sagitta he says " T h e y have two small black eyes and can look in all directions without turning their heads. They can even look down through their own transparent bodies." Typical copepods " h a v e one eye in the middle of the head which can look forward, upward and downward at the same time." Concerning f i s h - " u n d e r that lemon butter and parsley lies a truly noble beast, the master of the seas, a creature at the pinnacle of its evolution."

If you wish to talk to a dolphin in his native delphinese, or know when to avoid a shark and when to hit it on the nose you will find the latest information here, but G ~ S T A ~ ' S theory of neotony is also there, simply told, and there is page after page of good science underlying the oolourful style that makes the book light reading.

As it is no text book should you, a reader of Deep-Sea Research, read it too ? Yes, certainly. We cannot all be experts in all fields and this book can give you a quick glimpse into some of the other branches of marine biology that others find more fascinating than yours, and do it in a way that will be a relaxation. You must read it in an armchair, not in your institution library or at your bench. You could, i f only you had the time to do it, use the book as a basis for an extremely penetrating test of your abil i ty--or your librarian's abil i ty--for information retrieval. Test cases would average something in the order of ten to the page and only in a few is a hint given to the original. You could try to find the source of statements such as " o v e r a 10-year period a tiger shark may produce, use and shed as many as 24,000 saw-edged teeth " ; or " E m p e r o r Tiberius trod on a torpedo while bathing and discovered that the shock relieved the pain of his gout " ; or " f ive million commercial fishermen in the world netted, hooked and trapped some 50 million tons of seafood in 1963." This is not a criticism of the book, it would be unreadable to the public for whom it was intended if packed with references, but it would be a good exercise for you. You could also play a game of " t r u t h or not t r u t h " using your own definition of where t ruth slides imperceptibly into f ict ion--" if a man eats 10 lb of herring, only 1 lb can be built into his fat and muscle " ; " t h e otter wears the world's most valuable pelt " ; " d e e p cold waters underlying the tropics harbor bigger creatures than those found near the surface " ; " I n no field of international relations is agreement and compliance so difficult

Book Reviews 143

to achieve" (as in fishery regulation). " I f a flatworm cannot find a meal, it absorbs its own internal organs, becoming smaller and smaller until it expires."

In this book you will find a ready source of data which could be useful for popular lecturing; the accuracy of most you will not need. to question and in the rest you will find an intriguing challenge. We read. on p. 123, referring to cephalopods, " N o creature in the animal kingdom can match their amazing speed or repertoire of designs--the chameleon is slow and unimaginative by compar i son" and on p. 162 " Piscian ability to change livery, whether instantly or over a period of weeks, is un- equalled in the animal kingdom." The illustrations by GEORGE GEVOAN are usually apt, with appro- priate emphasis on the bizarre but annoying inaccuracies have crept in, for example the creature facing page 105 is certainly not Calanusfinmarchicus, and facing p. 67 is not a Calanus either. The photographs are mostly from Marineland of Florida and Miami Seaquarium.

Mr. CROMIE has himself been intrigued by the progress so far achieved and the various suggestions he has read about the future possibilities of fish farming and living underwater; he takes his readers wholehearted.ly into this world of speculations, culminating in his own sentence "Pe rhaps seaweeds will be hybridized to become tasty fruits and vegetables."

I have an armchair and I enjoyed reading this book; so will you. Marine Laboratory, J .H . FRASER Torry, Aberdeen.

Underwater observation using sonar. By D. G. TUCKER, Fishing News (Books) Limited, London, 1966, 144 pp. £2.

THIS book is an elementary treatment of the principles of sonar, which is taken to be any underwater acoustic echo-location system and thus includes echo-sounders. After discussing briefly the marine activities which require underwater information, the various means of obtaining such information and the significant part which sonar plays is clearly presented. Except for the fishing industry, the users of sonar will need to go much further for a complete understanding for their own application so the rest of the book is entirely directed to the fishery application.

The chapters on acoustic waves, beams and echoes and. on basic sonar systems are presented in simple physical terms. More discussion of the relation between the appearance of fish echo traces and properties such as frequency, gain, beam-width and ship speed would have been justified, but generally the treatment should satisfy and help the keen fisherman and the author has achieved his aim as stated in the preface. An adequate bibliography for further study is provided. Even with twenty photographic plates though the book does seem rather expensive at £2.

National Institute of Oceanography B.S. McCARTNEV