uncle supported Fibiger for his education. In 1883, at age 16, he passed his matriculation and was enrolled at the University of Copenhagen to study zoology and botany. He self-supported by teaching and working at the laboratories. He graduated in 1883. He continued for a medicine course and earned his medical degree in 1890. For a few months he worked as a physician at different hospitals, and also continued to study under Robert Koch and Emil Adolf von Behring in Berlin. Between 1891 and 1894, he was assistant to C. J. Salomonsen at the Department of Bacteriology of Copenhagen University. From 1894 he joined the Royal Danish Army Medical Corps, where he served till 1897. It was during his army service that he completed his doctoral thesis Research into the bacteriology of diphtheria. The University of Copenhagen awarded him a doctorate degree in 1895. He continued the diphtheria research at Blegdamshospitalet in Copenhagen, working as a Junior Physician. In 1897, he was appointed prosector at the Institute of Pathological Anatomy of University of Copenhagen. He was promoted to full Professor and eventually its Director in 1900. He also served as Principal of the Laboratory of Clinical Bacteriology of the Army from 1890 to 1905), and Director of the Central Laboratory of the Army and Consultant Physician to the Army Medical Service in 1905. Fibiger died of cardiac arrest in Copenhagen on 30 January 1928. Contributions Diphtheria research Fibiger's doctoral research was on diphtheria. He developed more efficient method of growing bacteria in a laboratory setting. He discovered that there were two different forms (strains) of the diphtheria bacillus (Corynebacterium diphtheriae) that produce two different symptoms, now called nasopharyngeal and cutaneous diphtheria. He also produced a blood serum against the disease. He was known for his methodological system of research. One of his experiments from 1898 in which he tested the blood serum for diphtheria is regarded by some as the first controlled clinical trial. While working as a Junior Physician in Blegdamshospitalet, he tested his diphtheria serum among hundreds (484) patients. As would be in modern clinical trial, he separated serum-treated and untreated patients, and found that more of untreated patients died than the treated ones. According to an article in The British Medical Journal in 1998: Cancer and parasitology research While studying tuberculosis in lab rats, Fibiger found tumors in some wild rats collected from Dorpat (officially Tartu, now