The advance of bacteriological science in the diagnosis and prevention of disease : being the inaugural lecture on the foundation of the new Chair of Pathology and Bacteriology, Mason University College, delivered October 9, 1899 / by R.F.C. Leith.

  • Leith, R. F. C. (Robert Fraser Calder)
Date:
1899
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Licence: Public Domain Mark

Credit: The advance of bacteriological science in the diagnosis and prevention of disease : being the inaugural lecture on the foundation of the new Chair of Pathology and Bacteriology, Mason University College, delivered October 9, 1899 / by R.F.C. Leith. 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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    ways, and we are not without evidence apparently supporting them all. Vide Fig. i. We have first the supposition that they are formed within the protoplasmic bodies of the bacteria themselves, i.e., intracellular, and either capable of being excreted in a modified or unmodified form, or incapable of being so excreted, requiring to be retained within the bacteria during their life time, and only being set free at their corporal death and disintegration. In the course of any disease a considerable quantity of any such toxines would naturally be set free, as large numbers of the germs are always dying. We have next the supposition that the toxines are formed not within the protoplasmic bodies of the bacteria, but outside them, in the fluids and tissues in which they lie, as the result of the changes which occur therein through the germs living upon them, i. e., that they are of extracellular formation. For instance, if a culture of a bacte- rium, say diphtheria, in bouillon be filtered through a porcelain filter, the germ free filtrate will, if certain precautions have been observed, be found to be highly toxic and able on injection into an animal to produce the symptoms characteristic of the disease. These toxic properties may have been acquired by the bouillon as the result of the bacteria living upon its constituents or as the result of direct excretion by the bacteria themselves; or further, the first substances produced may be of the nature of ferments, small in amount and powerless of themselves to do much harm, but capable of great after-effect in virtue of their digestive action, which when fully established comes to confer upon the fluid in which they are present toxic properties of great power. It is therefore apparent that we cannot draw any hard and fast line between intra- and extra-cellular toxines. In individual instances one or other method of formation may be predominant, but in many they may be combined. Further, more than one toxine may be formed by any one bacterium, or it may be that the particular toxine formed by any bacterium, is so complex and so unstable that it readily breaks up into bodies varying very much from one another, especially under different con- ditions of formation. We must, for instance, carefully refrain