The essentials of practical bacteriology : an elementary laboratory book for students and practitioners / by H. J. Curtis.

  • Curtis, Henry J.
Date:
1900
Catalogue details

Licence: In copyright

Credit: The essentials of practical bacteriology : an elementary laboratory book for students and practitioners / by H. J. Curtis. Source: Wellcome Collection.

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

    119/314 (page 101)
    PATHOGENIC ORQANISIVIS then mounted and stained, just as when using the gum-heezmg method (see Appendix B), the imbedding material (celloidm;, not bein- removed, as is found necessary in the case of paraffin sections. PATHOGENIC ORGANISMS The practical importance of the discovery of bacteria in diseased tissues was for long discounted by many eminent authorities, who re'-arded this invasion of the tissues as the result, and not the cause, of the disease. Even the constant presence of the Bacillus tuberculosis in phthisical sputum—to give a concrete instance—was considered by many wiiters of vast clinical experience to be a more or less accidental association, or epi-phenomenon, determined by the more favoui-able conditions for the growth of the organism in question m tissues of which the normal resistance and metabolism had been abeady profoundly modified by disease. The opposite view, in which every disease is explained on the germ theory, is equally incorrect. The truth, as usual, appears to be midway between these ex- tremes. Certain diseases from their clinical history and course are obviously parasitic in origin; and in such cases, even if the search for the organism has hitherto been unsuccessful, we may safely predict its discovery sooner or later. Many of the acute specific fevers, and syphiHs. are instances in point. As regards syphiHs, Lustgarten has, indeed, already described a special bacillus {Lustgarten's bacillus), but though further confirmation of this observation is desirable, the course of the disease is such as to ma,ke it practically certain that its microbic origin will, ere long, be clearly demonstrated. So for the acute specific fevers referred to above. And the same is probably true for certain forms of malignant disease (see p. 251). On the other hand, and for the same general reasons, it appears equally obvious that certain diseases, e.g. many of those arising in connection with the circulatory and nervous systems, are not parasitic in nature. In such cases, any associated organisms found are probably accidental in origin, or of quite secondary importance. Before a micro-organism can be considered to be the cause of a given disease, it should conform to the four well-known tests, or postulates of Koch—viz.: (i) It must always be present in the diseased tissues. (ii) It must be capable of reproducing the disease, when injected into a susceptible animal.