Arthur Henry Reginald Buller

Arthur Henry Reginald Buller could turn a moment almost invisible to the eye into an experimental problem. He was interested in how a fungus releases spores, how far they can travel, and which features of a fruiting body help them escape from between the gills or out of the tubes. Born in England in 1874, the botanist studied in Birmingham, Leipzig and Munich. In 1904 he became the first professor of botany and geology at the University of Manitoba in Winnipeg.

The most important part of his work is the multi-volume Researches on Fungi. Buller devised experiments with humidity, light and fruit-body orientation, and described the drop at a basidiospore’s base and the discharge trajectory. The catapult model in which the drop merges with a water film and abruptly shifts the centre of mass was proposed only in 1991 and later confirmed by ultra-high-speed imaging. The name ‘Buller’s drop’ honours his observation, not authorship of the complete modern mechanism.

Equally important was the question of what happens after discharge. A spore has to leave the surface of the hymenium, but must not strike the neighbouring gill. A minimal impulse is enough to cover that distance, and then the spore falls and is taken up by the air. Buller also analysed the rhythm of release and the influence of the shape of the fruiting body. The structure of a cap thereby ceased to be merely a character for identifying a species — it became a functional dispersal machine.

The University of Manitoba archive documents his research, his correspondence and his role in organising science at a young university. He also worked on cereal rusts, important for agriculture on the Canadian prairies. He therefore joined the mechanics of microscopic structures to economic problems, and published his descriptions with drawings and photographs that allowed others to check his conclusions.

Not all of Buller's interpretations have survived unchanged. His value lies, however, in having posed measurable questions about movement, timing and environmental conditions. Today's high-speed cameras show the details of spore discharge, but they perform the same intellectual work: revealing the physics hidden in an apparently motionless fruiting body.

Buller’s observation and the modern mechanism are not identical

Buller described the drop forming at the base of a basidiospore and the trajectory of discharge, but he did not demonstrate the modern surface-tension-catapult mechanism. Noblin and colleagues’ review and experiments state that Webster and co-workers proposed the coalescence model in 1991 and that ultra-high-speed video later supplied direct confirmation. At 50,000 frames per second, Buller’s drop merges with a flattened water layer on the spore; the decrease in surface energy rapidly redistributes mass and gives the spore momentum. Water condenses because sugars lower the water potential at the spore surface. The eponym credits Buller’s crucial observation, not authorship of the entire later physical explanation. The current sentence saying that he demonstrated the coalescence-driven centre-of-mass mechanism should therefore be corrected. His lasting contribution is the measurable geometry and timing that later technology could test.