A CASE OF NEED by Michael Crichton, writing as Jeffrey Hudson (Dutton: $18.95; 319 pp.). This 1968 effort by mega-author Michael Crichton, who would go on to bring us “Jurassic Park” and “Rising Sun,” is an interesting bit of literary history on several levels. Crichton fans will see how he got his start, including the beginnings of his rather didactic style: When was the last time you read a novel with footnotes and appendices--ones that you really needed to read to understand what’s going on? Crichton has always written instructive fiction, but this book is more blatant about it than his more stylistically sophisticated later work. The topic is abortion, which at the time Crichton wrote the novel was still illegal. His murder mystery revolves around a young woman, dead, it seems, from a botched abortion allegedly performed by a moralistic young doctor who believes in a woman’s right to have a choice. But his pal, and the hero of the book, can’t believe he would have mishandled the procedure--so he sets off to find the real villain. Crichton nicely handles the pomposity of the medical establishment. Feminists will applaud his overt pro-choice stance even if they are dismayed to find out whodunit. Fiction lovers will chuckle at the antics, and incredible persuasive powers, of pathologist and amateur detective Dr. John Berry, whose mere presence in a room seems to elicit from otherwise stoic sources an irrepressible urge to spill the beans. It’s all a bit too linear, but a lot of fun.