Background
Bohn was the son of a wealthy merchant family. He was born on 20 July, 1640 in Leipzig, Germany.
About 1665 Johannes Bohn received the doctorate from the medical school of Leipzig (present Leipzig University).
Bohn was the son of a wealthy merchant family. He was born on 20 July, 1640 in Leipzig, Germany.
Joannes Bohn studied medicine in Jena and Leipzig and about 1665 received the doctorate from the medical school of Leipzig (present Leipzig University).
In 1668 he was named professor of anatomy and surgery at Leipzig. In 1690 Bohn became a municipal physician, and the following year he was appointed a professor of practical medicine.
His twenty-six "Exercitationes physiologicarum" appeared at irregular intervals from 1668 on; these are doctoral dissertations, written by Bohn and disputed by various candidates for the doctorate. Most of the Exercitationes appeared in 1668; the rest appeared from time to time until about 1677. They were later reprinted as a whole in a pirated edition. Only a few copies of the work are available. Bohn later reworked these dissertations into a completely new composition which appeared in 1680 as "Circulus anatomicus-physiologicus seu Oeconomia corporis animalis", and was dedicated to Malpighi.
"The Exercitationes and the Circulus" show Bohn to have been an expert on the then-new anatomical and physiological discoveries. He cites contemporary authors almost exclusively and thereby proves himself one of the innovators in physiology who completely forsook the Galenic tradition. He describes and discusses all major functions of the body. He complements the knowledge gained from the literature with numerous firsthand experiments, for example, experiments on bile and the biliary tract, lymph ducts, heart contractions, pancreatic secretion, on the conjectured swelling of ligated nerves, and artificial perfusion of an excised kidney.
Bohn’s basic attitude was mechanistic in that he gave predominantly physical interpretations of vital processes. He especially esteemed Malpighi, Borelli, and Boyle. Bohn had an excellent knowledge of iatrochemistry as well, but he maintained a critical position against this doctrine. He condemned the ancient theory of qualities as unsuitable to the explanation of chemical processes. Wherever possible, he referred to Jan van Helmont’s theories of the fermentum and to those of "Sylvius on the acidum and the alcali". In his opinion, the process of digestion cannot be explained without the theories of iatrochemistry; with the help of spiritus and sal volatile, a fermentative transformation of food into chyle takes place. But he opposed a general explanation of physiological findings and clinical observations exclusively by these theories, and especially in his "De alcali et acidi insufficienlia" (1675) he explicates this attitude.
Bohn was a critical, truth-loving man who was so careful of his scientific reputation that on his deathbed he arranged for the destruction of all his unpublished writings.