Revised Dec. '2009. Karl Friedrich Meyer (May 19, 1884 – April 27, 1974) was a Swiss-born American veterinarian and physician (ad honorem) who splendidly fulfilled the definition of comparative pathologist. He attended what we consider in the USA elementary, middle and high schools in Basel where he started a broad education in the classics and such languages as Greek, Latin, French, English, and his native tongue, German. From his basic education all throughout he was to remain a renaissance man. He attended the University of Basel, and graduated from the University of Zurich where he studied biology and zoology. It was there that he discovered the concept of comparative medicine. He studied in Munich, Germany and returned to Switzerland to complete the curriculum at the Veterinary School in Bern in 1909. He went to the Veterinary Bacteriological Institute in South Africa to broaden his background in protozoology and epidemiology. There he studied theileriasis (Theileria) sp. and practiced the first ever formal autopsy in an elephant. His career was dedicated to work on infectious disease and because of the approach he took he more, than others, deserved the title of "microbe hunter"; he worked on the bacterial genus [[Brucella]] and the human and animals diseases it causes; he discovered the virus that causes western equine encephalitis and a number of similar viruses; he studied the epidemiology of coccidioidomycosis; he discovered the cause of psittacosis after falling ill with it himself. He developed a vaccine against pneumonic plague that was used in World War II and he developed food commercial processing standards, particularly the concepts of “D” and “z” values, a combination of microbiology and engineering, and preamble to food and bio-engineering, that formalized the prevention of canned foods botulism contamination. On the area of food microbiology he developed the modern protocols for the investigation of food-borne infections and intoxications which he pursued while investigating a famous outbreak of typhoid fever. Dr. Meyer was a faculty member at the Universities of Pennsilvania, California (Berkeley and San Francisco) and a staff member and eventual scientific director and general director of the Hooper Foundation until his retirement. Retirement in K. F.'s case was only a manner of speech as he remained extraordinarily productive until his death.