Gregor Mendel

Gregor Mendel presents his pea-hybrid experiments in two Brünn lectures

Roughly forty people heard him. Mendel later described their reaction not as silence but as “divided opinion.”

8 February 1865, in a school building

Gregor Mendel gave the first of two lectures to the Natural History Society of Brünn on 8 February 1865, in the Realschule building at 22 Jánská Street in Brünn, Moravia — now Brno, Czechia. It was a secondary school, not the monastery garden where the peas had grown.

In the first lecture he described his experimental approach and the behaviour of contrasting traits across successive generations of pea hybrids. About forty people were in the room.

The 8 March lecture, and how it landed

A month later Mendel resumed with cell formation, fertilization and seed production, using his crosses to explain how reproductive cells transmit traits between generations.

Contemporary reports do not describe total bafflement. One called the second lecture well received while noting that uncertain points required further investigation, and Mendel himself later recalled encountering divided opinion.

From lecture to print

The lectures were not the publication. Society secretary Gustav Niessl von Mayendorf asked for the manuscript, and the society printed it in its proceedings in 1866, in the volume designated number 4 for 1865.

A handwritten instruction on the surviving manuscript ordered forty personal offprints. The society sent the yearbook carrying the paper to 133 learned institutions.

Sources

Researched 23 Aug 2026 6 sources 2 audit passes, 1 issue open Date corrected

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Date corrected. The research places this at 1865-02-08.

What the sources leave uncertain

The event comprises two exact dates, February 8 and March 8. Because date_iso permits only one date, it records the first presentation; the second is integral to the event.
Reconstructions of exactly where the surviving 1866 paper divides between the two oral lectures differ, so the lecture-content descriptions rely on contemporary newspaper reports and modern scholarly reconstruction.