Rose and Carless's Manual of surgery for students and practitioners.

  • Rose, William, 1847-1910.
Date:
1912
Catalogue details

Licence: Public Domain Mark

Credit: Rose and Carless's Manual of surgery for students and practitioners. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    which may serve to unite the bacterial cell loosely with its neigh- bours. When such capsules become very prominent, large numbers of bacteria may become embedded in a gelatinous mass, known as a zooglcea. Capsule-formation is of some importance in diagnosis; the pneumococcus, for example, possesses a well-marked capsule when it occurs in blood or morbid exudates, and may thereby be distinguished from many organisms otherwise resembling it. The Methods of Reproduction which occur among the bacteria are extremely simple, nothing akin to sexual processes having been observed. In simple fission the cell becomes divided into two by a thin membrane, and these two portions develop into mature organisms. In many cases the two bacteria thus produced become entirely separated from one another; but in some species they remain more or less connected by means of the capsules described above, and in this way the individual bacteria become united into groups, which are more or less characteristic of the species. This process of division may take place with great rapidity, so that a suitable material which has become infected with one or two bacteria may contain vast numbers in the course of a few hours. Spore-formation is a more complicated process, and is found only in certain of the rod-shaped bacteria or bacilli. Bacterial spores are round or oval in shape, and are formed within the bacterial cell (endospores). They consist of a thick cell-wall filled with proto- plasm, which contains less water than the mature bacterium, and has, therefore, a highly refractile appearance when seen under the micro- scope. The shape and size of the spores have much diagnostic value; thus, the bacillus of tetanus has an almost spherical spore, which is distinctly larger than the diameter of the rod in which it is formed, whilst the spore of the anthrax bacillus is oval, and little or no broader than the rod itself. The position of the spore is also of importance. The spores of the tetanus bacillus are at the extreme end of the bacillus, giving it the appearance of a drumstick, whilst those of anthrax are central. Spores are to be regarded as resting forms adapted to maintain the life of the species under adverse con- ditions, and in this respect are analogous to the seeds of the higher plants. They resist drying to a far greater extent than do the bacteria themselves. Anthrax spores have been preserved in the laboratory for twenty years without loss of viability or virulence, whilst asporogenous anthrax dies in a few weeks when dried. They are also very resistant to heat. Most bacteria (when moist) are killed when exposed to a temperature of 60° C. for half an hour, whereas many spores are not killed by prolonged boiling. Lastly, they are very difficult to kill by means of antiseptics. Anthrax spores can be killed by immersion in i in 20 carbolic lotion, but only after several days. Of the bacilli of chief interest to the surgeon the B. tetani, B. anthracis, B. oedematis maligni form spores, and of those only the B. tetani in the body, whilst those of glanders, tubercle, diphtheria, typhoid fever, leprosy, influenza, and soft sore are asporogenous. Flagella are delicate filamentous extensions of the protoplasm.