August Krogh

Krogh married Birte Marie Jörgensen, a medical student and later a scientist, in 1905. The couple was blessed with four children, a son and three daughters. Their son became a Prosector of Anatomy at the University of Arahus. Marie died in 1943

August Krogh died on September 13, 1949, at the age of 74, in Copenhagen.

Schack August Steenberg Krogh was born on November 15, 1874, at Grenaa, Jutland, Denmark to Viggo Krogh and Marie, née Drechmann. His father was a shipbuilder.

A child prodigy, young Krogh’s interest in natural science developed early. When boys of his age played sports, Krogh immersed himself in experiments. He widely read books in botany, zoology, physics and chemistry.

As a young man, Krogh attended a lecture on medical physiology by Professor Christian Bohr. Impressed by the latter and inspired by his teacher friend William Sorenson, Krogh decided to make a career in physiology.

In 1893, Krogh enrolled at the University of Copenhagen as a student of medicine. However, he couldn’t keep himself away from studying zoology. In 1897, he started working under Professor Bohr at the Laboratory of Medical Physiology. In 1899, upon completing his examination in zoology, he received the appointment of an assistant to Professor Bohr.

In 1903, Krogh earned his doctorate degree. His thesis was on the respiratory exchanges of oxygen and carbon-dioxide in the lung and skin of frogs.

Following his doctorate degree, Krogh became highly interested in the gas exchange of the living organism. He submitted a paper on the pulmonary exchange of nitrogen wherein he demonstrated that free nitrogen played no role in respiratory exchanges. He backed up his work with careful experiments that used chrysalides, eggs and mice in a temperature-controlled apparatus. The work won him Seegan Prize of the Austrian Academy of Sciences.

Krogh adopted his own method of study and extended his research on respiration to other animals as well. During this time, Krogh believed that pulmonary exchanges took place through secretory processes regulated by nervous system. He also devised an instrument called tonometer and a device for microanalysis of gases.

In 1904, he published, with Bohr and K. A. Hasselbalch, a study on the relation between the carbon dioxide tension and the oxygen association of blood. His initial belief that lung secreted oxygen into the bloodstream was later given away for the new fundamental that pulmonary gas exchange was only dependent on diffusion.

Following the establishment of the fact that absorption of oxygen and elimination of carbon dioxide from the lungs is carried out by diffusion, a number of articles came up that criticized this new point of view and highlighted the problems. Krogh spent the following years publishing works concerning blood flow through lungs.

In 1908, a special associate professorship of zoo-physiology was created at the University of Copenhagen exclusively for Krogh. Leaving Bohr’s laboratory, Krogh set forth to make new discoveries and research in the field. In 1916, it was changed to an ordinary chair.

Krogh most remarkable work as a scientist and professor of zoophysiology came with his discovery of the mechanism of regulation of the capillaries in the skeletal muscle. The work helped in the better understanding of the anatomy and physiology of the capillary system. It also earned him a Nobel Prize in Physiology or Medicine in 1920.

Krogh was the man behind the ‘Krogh Principle’ which stated that ‘for such a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied’. The concept is till date dominant to those disciplines of biology relying on comparative method, such as neuroethology, comparative physiology, and functional genomics.