The microscope : its history, construction, and application, being a familiar introduction to the use of the instrument, and the study of microscopical science / by Jabez Hogg.

  • Hogg, Jabez, 1817-1899.
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: The microscope : its history, construction, and application, being a familiar introduction to the use of the instrument, and the study of microscopical science / by Jabez Hogg. Source: Wellcome Collection.

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

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    a healthy animal, produce the disease in question. 4. In the inoculated animal the same micro-organism must again be found. The chain of evidence will be still more complete if, from artificial culture, a chemical substance is obtained capable of producing the disease quite independently of the living organism. It is not enough to merely detect, or even artificially cultivate, a bacterium associated with disease. An endeavour must be made to establish the exact relationship of the bacteria to disease processes. In many Fig. 269.—Micro-Photograph ot Typhoid Fever Bacteria. Magnified 1000 x. Taken by Leilz's oil immersion ^^^i^^! ocular No. 4, and sunlight exposure of one minute. instances disease bacteria regarded as the actual contagia have been found, on a further searching inquiry, to be entii'ely misleading. It is almost needless to remind the enthusiast that the actual con- tagion of the disease must be fully demonstrated. Typhoid Bacillus (Fig. 269).—Eods 1 to 3 //.in length, and 5 to 'S /i in breadth, and threads. Spore-formation has not been observed, but the protoplasm may be broken up, producing appeai'ances which may be mistaken for spores. Actively motile, provided, some with a single and others with very numerous flagella, which are from three to five times as long as the bacillus itself. They stain readily in aqueous solutions of aniline dyes ; and grow rapidly at a temperature