Ferdinand Cohn

Ferdinand Cohn married Pauline Reichenbach in 1867.

He died on 25 June 1898, in Breslau.

Ferdinand Cohn was born on 24 January 1828, in the Jewish quarter of Wroclaw, Poland. At the time of his birth, the town was known as Breslau and it fell under the Prussian Province of Silesia under German Kingdom. He was the eldest of his parents’ three sons.

As a child. Ferdinand was shy, studious and sensitive. His father, Issak Cohn, was a wealthy merchant, who recognized his talent early in life and spared no effort to nurture it. Ferdinand retained a sad memory of his overtly studious childhood.

Ferdinand began his education at the age of four. In 1835, he was enrolled at Maria Magadalena Gymnasium. In the beginning he advanced quite rapidly. Unfortunately he developed hearing impairment at the age of ten and after that his progress slowed down a bit. It also made him suffer emotionally.

He soon overcame such emotional impediment and entered the University of Breslau in 1842. He first took up philosophy, but encouraged by German botanist Heinrich Goppert, he soon switched to botany. However, because he was a Jew, he was not allowed to take the final degree examination.

Therefore, he shifted to the more liberal University of Berlin in October 1846 and received his doctoral degree in botany from there on 13 November 1847 at the age of 19. He spent two more years in Berlin studying botany under noted scientists of that time.

In 1850, Ferdinand Julius Cohn began his career as a Privatdozent at the University of Breslau. This was an exciting time for the botanists. Shortly before this, Matthias Schleiden had established his cell theory and Hugo von Mohl had talked about protoplasm in plant cells.

Cohn, impressed by these revolutionary ideas, decided to focus on unicellular algae. He also believed that one must start by studying the cellular structure of simpler organism if one wanted to gain insight into the cellular structure of higher organism.

The third important factor was that, in 1848, Heinrich Goppert, under whom Cohn had studied botany at Breslau, had asked him to concentrate on algae. He had hoped that Cohn would be able to contribute to the study of flora of the cryptogamous plants of Silesia.

Therefore in 1850, Cohn began his study on unicellular algae Protococcus pluvialis with special emphasis on protoplasm. His father, impressed by his enthusiasm, bought him a powerful microscope; something the University of Breslau did not have. Shortly, it became his main research tool.

He believed that, just like any other plants, the stages of growth of microscopic organisms could be learned only by directly observing them. Accordingly, he used his microscope to examine each stage of their development. His description of the life histories of several algae species remains equally important today.

Cohn’s introduction of a systematic study of the life histories of microorganisms like bacteria and algae is probably his most important work. He is also remembered for his discovery of the formation as well as germination of endospores in Bacillus subtilis.

During that time, scientists could not explain how Bacillus subtilis could reappear within a short period even after the container was thoroughly boiled because bacteria cannot survive in such high temperature. They began to believe that it was because bacteria could generate spontaneously.

Cohn refuted the idea as a fallacy and established that the Bacillus survived boiling temperature simply by genereting thermo-resistant spores. Afterwards they went back to their normal reproductive stages.