Parke-Davis is a subsidiary of the pharmaceutical company Pfizer. Although Parke, Davis & Co. is no longer an independent corporation, it was once America's oldest and largest drug maker, and played an important role in medical history. In 1970 Parke-Davis was acquired by Warner-Lambert, which in turn was acquired by Pfizer in 2000. History Parke, Davis and Company was founded in Detroit, Michigan by Dr. Samuel P. Duffield, a physician and pharmacist. In 1860, Dr. Duffield owned a small drugstore at the corner of Gratiot and Woodward Avenues. Dr. Duffield made a variety of pharmaceutical preparations, including Hoffman’s anodyne and mercurial ointment, but was overwhelmed by the operations of the business. Dr. Duffield and Hervey Coke Parke formed a partnership in October 1866, with George S. Davis becoming a third partner in 1867. Parke was a businessman looking for business opportunities and Davis, an ambitious man with skills in sales. Duffield withdrew in 1869 because of poor health and an interest in practicing medicine. The partnership adopted the name Parke, Davis or Parke-Davis in 1871, and was formally incorporated as Parke, Davis & Company in 1875. In 1871, the company sent expeditions to Central and South America and the West Indies in search of medicinal plants. The company produced an herbal laxative drug Cascara found from Native Americans in the Pacific Northwest. It was once the world's largest pharmaceutical company and is credited with building the first modern pharmaceutical laboratory and developing the first systematic methods of performing clinical trials of new medications. The Parke-Davis Research Laboratory is a National Historic Landmark; the surrounding Parke-Davis and Company Pharmaceutical Company Plant is on the National Register of Historic Places. The production facility on Parkdale Road in what was then Avon Township, Michigan (site now in Rochester, Michigan) was also a landmark in that vicinity and is now used by PAR Pharmaceuticals. In the 1950s, Parke-Davis employed Jonas Salk as a consultant on vaccine adjuvants. Parke-Davis was also involved in manufacturing the polio vaccine. It took Salk much effort to convince Parke-Davis to follow his production protocols exactly. For about six months Parke-Davis had the exclusive contract to produce the vaccine for field trials but in February 1954 the National Foundation for the Prevention of Polio reneged on the contract and opened vaccine production to other companies as well. Parke-Davis commissioned Detroit illustrator Robert Thom to produce 40 illustrations for the series,