SPECIALIZATION MAY BE the peculiar affliction of many individuals and organizations at Harvard, but in its concert Saturday the Bach Society Orchestra convincingly demonstrated that it is not one of those. To open the 1977-78 season, Conductor Christopher Wilkins led the ensemble through an eclectic blend of periods and styles: a Baroque suite, a nineteenth-century overture and concerto, and a minor twentieth-century choral masterpiece.

The program opened with J.S. Bach's Overture No. 3 in D major, a sumptuous orchestral suite in the style of the French Baroque. The work's first movement separates a stately introduction and conclusion with a glittering allegro. Here Wilkins's interpretation was scrupulously authentic, notably in the crisply dotted rhythms, and the orchestra responded with elegance and delicacy. The one glaring weakness here and throughout the entire piece came from the crucial (and difficult) D trumpets: instead of flashing above the orchestra with fluid precocity, they squeaked and quavered vaguely in the background.

The overture is followed by four briefer movements. Of these, the most famous is the air, better known--and better forgotten--in its romanticized solo version as the "Air for the G String." The orchestra played superbly: enormous lyricism and sweetness never obscured the tightly-crafted framework, the silvery line of the upper strings poised against the muted rhythms of the bass. Far from being "mushy" or banal, Wilkins's reading was almost reverent, hushed and glowing.

The three dance movements that followed were less satisfactory. There was still vigor and clarity (the lacy harpsichord was an especially fine touch), but Wilkins never permitted the orchestra to flaunt the music's bravura potential. Unfortunately, his thoughtful, courteous reading blunted the brilliance, the hard edges, of a work which should above all be diamond-hard and sparkling.

In the next work, Max Bruch's Violin Concerto No. 1 in G minor, the orchestra was joined by soloist Stephen Chan. The concerto includes the traditional three movements; the first has something of the quality of a dramatic dialogue, alternating the tragic declamation of the solo instrument with the orchestra's solemn thunder. Chan played with technical elan but a rather lifeless tone that occasionally made it hard to distinguish him from the rest of the orchestra. But he was more in command of the languorous Adagio which followed. This exquisite lamentation is less a dialogue than a duet, with the solo instrument soaring and flickering above the yearning orchestral line. Chan chose to be restrained rather than impassioned: his cool and liquid voicing, though played with enormous suppleness and grace, was if anything too emotionally detached. On the other hand, the orchestra was all the more poignant for its gracious deference to the soloist.

THE THIRD MOVEMENT was a decided come-down, although that admittedly was largely the composer's fault. It was a rather silly piece of music--all surface, full of melodramatic cadences and changes of tempo. Although both Chan and the orchestra played with firmness and polish, nobody seemed to know what to do with the music--and their hesitance did nothing to make Bruch's bombastic posturing any more convincing.

The overture from Beethoven's "Incidental Music to Goethe's Egmont" opened the second half of the program. It was a work of dark splendor. The jaggedly imperious strings stood in stark contrast to the plaintive radiance of the woodwinds. Saturday's performance had a nobly crafted strength; the orchestra responded to Wilkins's tight command with fervor and conviction.

For the final work, Ralph Vaughan Williams's "Serenade to Music," the Bach Society was joined by the Harvard University Choir. Written to a Shakespeare text in 1938, the serenade fortunately has become a gem of the choral repertoire, a consummately felicitous welding of poetry and music. The Bach Society's performance was truly gorgeous--all moonlight and velvet shadow. The chorus blended into a cool wave of sound, plumbing the music's dreamy depths without sacrificing a sparkling diction. The soloists, particularly soprano Ellen Burkhardt, were uniformly fine. The orchestra matched them in ethereal luster as a glossy violin solo, the ripple of a harp, and a punctuation of prancing fanfares closed the evening in shimmering enchantment.