The development of one's own silk mills is reason to brag, and Zegna cashed in on its recent and growing ZegnaSilk project with a Spring collection devoted entirely to the fabric. "The cashmere of summer," Anna Zegna, granddaughter of the original Ermenegildo, called it. Silk showed up in every look: mixed into perforated knits, shining in shantung suiting, wafting in shirts printed with tropical banana or mango leaves. To counteract some of the floatiness, the silhouette was sharper: tapered, high-waist pants with stitched pleats, high-fastening, wide-lapel jackets with strong shoulders, all in shades of tobacco, navy, burgundy, and cream. After the show, Mrs. Zegna was enthusing about the Italian taste for glamorous eccentricity, mentioning men dressed for Capri and other vacation climes. Last season, the label assured its clients that even though the Fall collection's theme was ski-trip chic, the EZ man was never far from his Blackberry. Something of the opposite effect was achieved today, when for the finale every model shed his jacket for a 30-strong parade of rippling silk shirts. It may take a minute for Zegna's customers to match step with this new swagger.