Knits to keep you in stitches

Not since the first needles interlocked to start the knit one, purl one chain of events that led to the birth of the sweater have such momentous things been happening in knittery.

The year's boom, which has been described as the "sweatering of America," encompasses all sorts of knitwear, from socks on up. The diversity in yarns, stitches, and styles available seems unequaled in human memory.

At every price level, knitted clothes reflect an energized outpouring of imagination and talent which, in some other areas of fashion, appears to be dormant. The selection is vast, with attractive choices for different tastes and pocketbooks. For many a shopper, adding a sweater or two to her wardrobe will be an idea she is unable to resist.

Among the most appealing pullovers are the graphics and pictorials known as Art Knits, many of them British imports. Costly one-of-a-kind handmade wools are often three-dimensional scenes, with trapunto areas depicting hilly countrysides and crocket wool appliqued for trees.

The more serious basics -- the Shetlands and lamb's wools -- have been updated in color, detail, and pattern. Lavender, lemon yellow, persimmon, and emerald are among the brights in cable-knit and Fair Isle crew necks. Ralph LAuren, whose sweaters are widely copied, has given his puff-sleeved Shetland cropped cardigan a crochet-edged round collar. Perry Ellis, another designer whose knits set trends, has added capelets and ripple collars to his fluffy mohair sweaters.

Ellis and LAuren (and also Donna Karan for Anne Klein) have produced enlarged versions of the classic argyle in Vneck pullovers, vests, and twin sets. A number of similar outsized diamond-pattern sweaters have already turned up in stores' junior departments at far less expensive prices.

Oversized sweaters (often in mohair, the yarn of the year) come in geometric color splits as well as folkloric designs. The Scandinavian reindeer, enlarged, is a favored motif. Patterned stripes, raised polka dots, and intarsia knit animals and clown faces are other piquant ideas being used.

Most new knits tend to be bulky. In most instances, popcorn and cable come off better with thick yarns than do lacy stitches. But a knit whiz designer like Joan Vass, who continues working with chenile and mixtures of angora with lighter yarns, can manage to fashion long torso dresses, tunics, and blousons as gracefully as if she were working with fabric.

The sweater vogue ranges far and wide, extending to big- shouldered loose jackets and tuxedo-collared coast as well as to one-and two-piece dresses, some of which have Fair Isle yokes or lace collars.