Post-graduate course at Queen's College, Birmingham : two lectures on the general pathology of tubercle, with especial reference to the question of infection / by Gilbert Barling.

  • Barling, Harry Gilbert, 1855-1940.
Date:
[1891]
Catalogue details

Licence: Public Domain Mark

Credit: Post-graduate course at Queen's College, Birmingham : two lectures on the general pathology of tubercle, with especial reference to the question of infection / by Gilbert Barling. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    especially if the staining fluid be warmed, and for clinical pur- poses a few minutes is sufficient. We now have the whole section or layer of sputum coloured red, and the stained material is exposed for a brief period to the action of a rather strong acid and subsequently is washed in alcohol. The effect of this is to remove the red stain from practically everything but the bacilli, which, as I have already mentioned, hold their stain tenaciously once they have received it. For convenience of examination it is usual to employ what is known as a counter stain, for example, methylene blue. A dilute solution of this stain is applied to the section or sputum, and the material (with the exception of the bacilli which are still red) absorbs the blue stain. The specimen is then mounted in the usual way for examination by the microscope. For this examination a good lens, an 8th or a ioth is desirable, or what is still better, a 12th oil immersion; and it is of advantage, indeed in some cases a necessity, that a special illumination of the specimen shall be made by an Abbe's substage condenser or some similar arrangement, the advantage gained being that the structure picture is obscured and the colour picture well brought out, the stained bacilli being thus more readily discovered. The bacillus is rod-shaped, in length about 7J00 of an inch (somewhat less than half the diameter of a red blood corpuscle) and it is generally somewhat bent, sometimes distinctly curved. With high powers of the microscope, a 12th oil immersion, or with a first-rate 8th or ioth, the bacillus is sometimes seen to be distinctly nodular, the appearance being probably due to spores by means of which the organism is reproduced. The spores resist staining even more strongly than the rest of the bacillus, we thus have parts of the rod-shaped body stained and part unstained, the effect being sometimes to give the appearance of a chain of micro-cocci. So far as is known at present the tubercle bacillus has no power of independent movement, and it is either carried passively by the blood or lymph stream, once it has found its way into those channels by the breaking down of the tubercle; or it is taken up into the interior of a wandering