Definition of Ehrlich, Paul

Ehrlich, Paul: (1854-1915) Renowned German scientist and physician. Born near Breslau, Ehrlich got his start there working in the laboratory of his cousin, Carl Weigert, a pathologist who pioneered the use of aniline dyes as biological stains. Ehrlich became interested in the selectivity of these dyes. He showed that they react specifically with cells and subcellular structures and that all of these dyes can be classified as basic, acid or neutral. His classic work on the staining of granules in white blood cells helped lay the foundations of hematology and histology.

Following a bout with tuberculosis, Ehrlich developed a method for staining the bacillus that caused his disease. His method became the basis of the method still used today to stain and identify the bacillus of tuberculosis. From Ehrlich's work also came the basis for the Gram stain for bacteria, a key technique in bacteriology.

Ehrlich did important work on immunology. He also showed that the toxin-antitoxin reaction is accelerated by heat and retarded by cold, as are all biochemical reactions. He found that the content of antitoxin in sera varied so much that it was necessary to establish a standard by which their content could be measured. This he did by using units related to a fixed and invariable standard. His method formed the basis of the future standardization of sera and many other biologic products.

Ehrlich looked for chemical agents to use against disease. His research programs were guided in part by his theory that the germicidal capability of a molecule depended on its structure, particularly its side-chains, which could bind to the disease-causing organism. Ehrlich was in search of what he called the "silver bullet."

The most successful products of this quest were Salvarsan (1909-1910) and Neosalvarsan (1912), the most effective drugs for treating syphilis until the advent of antibiotics. There is general agreement that Paul Ehrlich was one of the great medical researchers of the 19th and early 20th centuries (and all time). In 1908 he shared the Nobel Prize in Physiology or Medicine for his work on immunology.

This Paul Ehrlich is not to be confused with Paul R. Ehrlich (1932-), the American evolutionary and population biologist.