Press Release

Corning Incorporated Completes Spin-off of Quest Diagnostics and Covance to Shareholders

CORNING, NY, January 2, 1997 – Corning Incorporated (NYSE: GLW) announced today that it effected by delivery (Harris Trust and Savings Bank as Distribution Agent), the distribution of approximately 28,040,000 shares of the Common Stock of Quest Diagnostics Incorporated (NYSE: DGX) and approximately 56,080,000 shares of the Common Stock of Covance Inc. (NYSE: CVD) to Corning Incorporated shareholders of record on December 31, 1996 (11:59 p.m.). This distribution of the Common Stock of Quest Diagnostics (formerly known as Corning Clinical Laboratories Inc.) and Covance (formerly known as Corning Pharmaceutical Services) is the final step in the spin-off of these former Corning Incorporated subsidiaries as independent publicly traded companies.

As previously announced, one share of Quest Diagnostics Common Stock was distributed for every eight shares of Corning Common Stock, and one share of Covance Common Stock for every four shares of Corning Common Stock held on December 31, 1996. The distribution is based on the approximately 224,300,000 shares of Corning Common Stock outstanding on December 31, 1996, and participating in the distribution.

On November 20, 1996, the Board of Directors of Corning Incorporated approved the final terms of a strategic plan to distribute to Corning shareholders the clinical laboratory business being conducted by its wholly owned subsidiary, Quest Diagnostics, and the contract research business being conducted by Quest Diagnostics' wholly owned subsidiary, Covance.

Corning shareholders will receive stock certificates for whole shares and cash payments for fractional share interests in mid-January, 1997.

Corning Chairman and Chief Executive Officer Roger G. Ackerman said, "The new Corning is fully positioned to concentrate on its core communications and technologies businesses, where the company can leverage its materials and process technology, and achieve and sustain competitive advantages and superior financial returns and growth over time.

"We believe this dramatic strategic move also has positioned Covance and Quest Diagnostics to be more competitive and successful, as each company's management team will be able to focus resources and capabilities on the demands of their particular businesses," concluded Mr. Ackerman.

Quest Diagnostics, with headquarters in Teterboro, NJ, is one of the largest clinical laboratories in the country. It performs its tests in 17 regional labs and 14 smaller branch labs across the US and in a branch lab in Mexico City. The tests it performs on human tissue and fluids help doctors and hospitals diagnose, treat and monitor diseases from AIDS to cancer. Quest Diagnostics' 18,700 employees process and provide data on more than 60 million specimens annually. Its center for research and development, Nichols Institute, develops and uses specialty tests using advanced technology in such fields as endocrinology, oncology and genetic testing. In addition, Quest Diagnostics operates 850 patient service centers around the country to collect the specimens.

Covance, with headquarters in Princeton, NJ, is one of the world's largest and most comprehensive biopharmaceutical development service companies, with annual revenues in 1995 of more than $400 million, operations in 15 countries, and currently over 5,000 employees worldwide. Covance is dedicated to providing preclinical services, health economics and outcomes research, central laboratory services, biotechnology manufacturing, pharmaceutical packaging services, clinical and periapproval services and research products to the world's pharmaceutical, biotechnology, and medical device companies.

Established in 1851, Corning Incorporated creates leading-edge technologies for the fastest growing segments of the world's economy. Corning manufactures optical fiber, cable and components, high-performance glass and components for televisions, and other electronic displays for communications and communications-related industries; advanced materials for the scientific, life sciences and environmental markets; and consumer products. Corning's total revenues from continuing operations in 1995 were $3.3 billion.