. A text-book of bacteriology. Bacteriology. BACILLI IN CHRONIC INFECTIOUS DISEASES. 469 â ous in tuberculous growths of recent origin, and often cannot be demonstrated, by microscopical examination, in caseous material from the centre of older nodules. But such material, when inocu- lated into susceptible animals, gives rise to tuberculosis, and the usual inference is that it contains spores of the tubercle bacillus. Morphology.âThe tubercle bacilli are rods with rounded ends, of from tc /< in length, and are commonly slightly curved or bent at an angle; the diameter is about f
. A text-book of bacteriology. Bacteriology. BACILLI IN CHRONIC INFECTIOUS DISEASES. 469 â ous in tuberculous growths of recent origin, and often cannot be demonstrated, by microscopical examination, in caseous material from the centre of older nodules. But such material, when inocu- lated into susceptible animals, gives rise to tuberculosis, and the usual inference is that it contains spores of the tubercle bacillus. Morphology.âThe tubercle bacilli are rods with rounded ends, of from tc /< in length, and are commonly slightly curved or bent at an angle; the diameter is about In stained preparations unstained portions are frequently seen, which are generally believed to be spores, but this is by no means certain. From two to six of these unstained spaces may often be seen in a single rod, and owing to this al- ternation of stained and unstained portions the bacilli may, under a low power, be mistaken for chains of mi- crococci The rods are usually soli- tary, but may be united in pairs, or . , , , . , â ⢠,1 / Fio. 114. â Bacillus tuberculosis. m short chains containing three or four x 1,000. From a photomicrograph, elements. In old cultures irregular forms may be observed, the rods being sometimes swollen at one extremity, or presenting the appearance of having a lateral bud-like projectionâ^involution forms. The staining characters of this bacillus are extremely important for its differentiation and recognition in preparations of sputum, etc. Unlike most microorganisms of the same class, it does not readily take up the aniline colors, and when stained it is not easily decolorized, even by the use of strong acids. The failure to observe it in tuber- culous material, prior to Koch's discovery, was no doubt due to the fact that it does not stain in the usual aqueous solutions of the aniline dyes. Koch first recognized it in preparations placed in a staining fluid to which an alkali had been addedâsolution of methylene blue with caustic p
Size: 1584px × 1578px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectbacteri, bookyear1901
