"Why not space flowers?" asks one of the characters in the new "Invasion of the Body Snatchers." "Why do we always expect them to come in metal ships?"

Why indeed? Insidious space flowers provide more chills than a whole flotilla of whizzing, whirling gizmos in this faithful remake of Don Siegel's 1956 sci-fi classic. From these alien little blossoms mighty protoplasms grow, and the result is a delicious horror film that will delight fans of the original as well as those seeing the tale for the first time.

Director Philip Kaufman and producer Robert Solo cleverly entwine such elements as disorienting low-angle shots, an ominously pulsating soundtrack and eerie gloom with the tried-and-true plot and come up with a tight thriller. Essentially, creatures hatched from pods replace sleeping humans with emotionless reproductions. The pod-producing flowers are everywhere, and nature subverted becomes beautifully sinister with wickedly insinuating tendrils. Every cloud, every shadow is pregnant with meaning, sweeping the viewer along as the ominous tension builds.

At the core is Donald Sutherland, who, as Mattew Brunell, must try to keep his head -- and body -- while all about him are losing theirs. He's that sci-fi cornerstone: the mild man of reason who inadvertently discovers that aliens are taking over. Moved to violence by his morality, he must fight the evil to the end or die trying. Sutherland does the genre justice. His homely-handsome face eloquently reflects his growing sadness and desperation as he helplessly watches humanity being drained out of the human race. Brooke Adams ("Days of Heaven") is a bit stiff as The Girl. A sort of latter-day Ali MacGraw, she's not helped any by lines like "I can't go on anymore." One almost hopes Sutherland will reach out to the more expressive Veronica Cartwright, who plays better half to Jeff Goldblum's neurotic poet.

Cartwright and Goldblum are another couple of cognoscenti who try to escape the pod people with Sutherland and Adams. One of the film's most frightening moments occurs when they discover a creature forming into Goldblum's image in Cartwright's bathhouse. From here on in the plot thickens with bacterial slime and peaks in an incredible sequence where we actually see the creatures orgasmically disgorged from their pods in a grand birth noir ! Warning: the ensuing gore, particularly when Sutherland smashes his own pod-twin, may prove too graphic for some youngsters despite the PG rating.

In jokes abound, and the hero of Siegel's version, Kevin McCarthy, is shown in a scene that purely serves as an ode to the original. Siegel himself appears in a cameo as a cabdriver. Homage is also paid to scifi's new boy-wonders with scenes that obviouly echo Steven Spielberg's "Close Encounters" and George Lucas' earlier "THX-1138."

Made during the height of the McCarthy era, Siegel's film was a perfect metaphor for its time. It expressed the paranoia created by the threat of the enemy within -- i.e ., people running through the streets screaming "He's not my brother anymore." Here the updated metaphor is alienation, and the setting has been changed from small-town California to me-decade mecca San Francisco. The appeal of the pod people, in the words of a pop-psychology poobah played by Leonard Nimoy, is that there's "no anxiety, no hate, no love." It's the ultimate gestalt , a psychological enema, and the willingness with which the populace succumbs to it is especially chilling in the wake of Jonestown.