Georges-Louis Leclerc, Comte de Buffon (1707-1788) and John Turbeville Needham (1713-81)

Speculation followed Leeuwenhoek’s work and a century later the embers of the spontaneous generation controversy burst into flames once again.  The celebrated French naturalist Georges-Louis Leclerc, Comte de Buffon conjured up a picture of unseen organic particles floating in the air.  When these came together the ‘animalcules’ were formed and they, by the same process, formed larger organisms.  Thus all organisms were thought to arise by spontaneous generation from an invisible dust that covered the earth.  But Buffon’s contemporaries laughed at his support for spontaneous generation.  In an age when proof came from experiment, such speculations were not taken seriously. 

Georges-Louis Leclerc, Comte de Buffon (1707-1788)

Others like the English Catholic priest John Needham, performed more experiments and their conclusions were treated with greater respect. 

Needham heated various vegetable infusions such as almond seeds in water, placed them in test tubes, sealed to make them airtight, and then heated them again.  In a few days he saw under the microscope, many small particles moving about in the broth. Could they be tiny animals?  Similarly the black powder from rotten corn seemed to come alive when moistened with water and in this case Needham believed the moving particles to be a type of microscopic eel.  Where had these moving particles come from? Had they entered the sealed test tube from the air outside or were they produced by the infusions in the vessels?

Buffon and Needham with others carrying out scientific experiments   (Buffon is seated at the head of the table talking to Needham who is beside him)

Needham devised an experiment which he thought would settle this. He poured gravy from roasted meat into a vessel, firmly corked to seal it from insects or eggs floating in the surrounding air.  To destroy any living thing in the air inside the flask, he heated it strongly.  Yet despite all this, he said the infusion soon showed a swarm of moving microscopic animals.  He concluded true animals had arisen by spontaneous generation.

Bibliography

David C. Goodman, The Enlightenment: Deists and Rationalists: Science and Belief unit 7, OUP 1974

Grace Monger and Richard Gliddon eds, The Perpetuation of Life: revised Nuffield biology text 4, Longman 1975

G. Rattray Taylor,  The Science of Life, Thames and Hudson 1963