Doctor

Paul Ehrlich was born on March 14, 1854 at Strehlen, in Upper Silesia*, Germany. He was the son of Ismar Ehrlich and his wife Rosa Weigert, whose nephew was the great bacteriologist Karl Weigert.

Ehrlich was educated at the Gymnasium at Breslau and subsequently at the Universities of Breslau, Strassburg, Freiburg-im-Breisgau and Leipzig. In 1878 he obtained his doctorate of medicine by meansof a dissertation on the theory and practice of staining animal tissues. This work was one of the results of his great interest in the aniline dyes discovered by W. H. Perkin in 1853.

In 1878 he was appointed assistant to Professor Frerichs at the Berlin Medical Clinic, who gave him every facility to continue his work with these dyes and the staining of tissues with them. Ehrlich showed that allthe dyes used could be classified as being basic, acid or neutral and his work on the staining of granules in blood cells laid the foundations of future work on haematology and the staining of tissues.

In 1882 Ehrlich published his method of staining the tubercle bacillus that Koch had discovered and this method was the basis of the subsequent modifications introduced by Ziehl and Neelson,which are still used today. From it was also derived the Gram method of staining bacteria so much used by modern bacteriologists.

In 1882 Ehrlich became Titular Professor and in 1887 he qualified, as a result of his thesisDas Sauerstoffbedürfnis des Organismus (The need of the organism for oxygen) as a Privatdozent (unpaid lecturer or instructor) in the Faculty of Medicine in the University ofBerlin. Later he became an Associate Professor there and Senior House Physician to the Charité Hospital in Berlin.

In 1890 Robert Koch, Director of the newly established Institute for Infectious Diseases, appointed Ehrlich as one of his assistants and Ehrlich then began the immunological studies with which his name will always be associated.

At the end of 1896 an Institute for the control oftherapeutic sera was established at Steglitz in Berlin and Ehrlich was appointed its Director. Here he did further important work on immunology, especially on haemolysins. He also showed that the toxin-antitoxin reaction is, as chemical reactions are, accelerated by heat and retarded by cold and that the content of antitoxin in antitoxic sera varied so much for various reasons that it was necessaryto establish a standard by which their antitoxin content could be exactly measured. This he accomplished with von Behring's antidiphtheritic serum and thus made it possible to standardize this serum in units related to a fixed and invariable standard. The methods of doing this that Ehrlich then established formed the basis of all future standardization of sera. This work and his otherimmunological studies led Ehrlich to formulate his famous side-chain theory of immunity.

In 1897 Ehrlich was appointed Public Health Officer at Frankfurt-am-Main and when, in 1899, the Royal Institute of Experimental Therapy was established at Frankfurt, Ehrlich became its Director. He also became Director of the Georg Speyerhaus, which was founded by Frau Franziska Speyer and was built next-door toEhrlich's Institute. These appointments marked the beginning of the third phase of Ehrlich's many and varied researches. He now devoted himself to chemotherapy, basing his work on the idea, which had been implicit in his doctorate thesis written when he was a young man, that the chemical constitution of drugs used must be studied in relation to their mode of action and their affinity for the cells ofthe organisms against which they were directed. His aim was, as he put it, to find chemical substances which have special affinities for pathogenic organisms, to which they would go, as antitoxins go to the toxins to which they are specifically related, and would be, as Ehrlich expressed it, «magic bullets» which would go straight to the organisms at which they were aimed.

To achieve this,...