Fermentation and its bearings on the phenomena of disease : a discourse delivered in the City Hall, Glasgow, October 19th 1876 : under the auspices of the Glasgow Science Lectures Association / by John Tyndall.

  • Tyndall, John, 1820-1893.
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: Fermentation and its bearings on the phenomena of disease : a discourse delivered in the City Hall, Glasgow, October 19th 1876 : under the auspices of the Glasgow Science Lectures Association / by John Tyndall. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    selves belong, there is another living world requiring the microscope for its discernment, but which, nevertheless, has the most important bearing on the welfare of the higher life-world. And now let us reason together as regards the oiigin of these bacteria. A granular powder is placed in your hands, and you are asked to state what it is. You examine it, and have, or have not, reason to suspect that seeds of some kind are mixed up in it. But you prepare a bed in your garden, sow in it the powder, and soon after find a mixed crop of docks and thistles sprouting from your bed. Until this powder was sown neither docks nor thistles ever made their appearance in your garden. You repeat the experiment once, twice, ten times, fifty times. From fifty different beds after the sowing of the powder you obtain the same crop. What will be your response to the question proposed to you ]• I am not in a condition, you would say, to aifirm that every gi'ain of the powder is a dock-seed or a thistle-seed; but I am in a condition to aflirm that both dock and thistle .seeds foi-m, at all events, part of the powder. Supposing a succession of such powders to be placed in your hands with gi-ains becoming gradually smaller, until they dwindle to the size of impalpable dust particles; assuming that you treat them all in the same way, and that from every one of them in a few days you obtain a definite crop—it may be clover, it may be mustard, it may be mignonette, it may be a plant more minute than any of these, the smallness of the particles, or of the plants that spring from them, does not affect the validity of the conclusion. Without a shadow of misgiving you would conclude that the powder must have contained the seeds or germs of the life observed. There is not in the range of physical science an experiment more conchisive nor an inference safer than this one. Supposing the powder to be light enough to float in the air, and that you are enabled to sec it there just as plainly as you saw the heavier powder in the palm of your hand. If the dust sown by the air instead of by tlio hand produce a definite living crop, with the same logical rigour you would conclude that the germs of this crop must be mixed with the dust. To take an illustration : the spores of the little plant