Whether bisexuality exists as a psycho-social phenomenon or bisexuals are simply homosexuals in transition is the question posed but never satisfactorily answered here. Analyst Klein seems rather more anxious to fill a gap in the Library of Congress listing than to demonstrate that bisexuals constitute a third sexual category and that they can, indeed, be well adjusted. In the chapter entitled ""The Healthy Bisexual,"" his prime example is a woman who fantasizes about female breasts while making love to a man--who is himself a transvestite willing to have hormone therapy in order to please her by growing breasts. Hardly the picture of health. Klein's cases seem to be drawn, in the main, from his patient roster. Which would indicate some distress if not outright confusion on the part of the people involved. There is a book to be written on this subject--still. And, please, without a list of ""Bisexuals--Past and Present,"" such as Alexander the Great, Vita Sackville-West, and Janis Joplin.