Licence: Public Domain Mark
Credit: Surgery. 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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![The Spirilla arc spiral, scrcw-shapcd organisms, consisting of long chains twisted like a corkscrew and possessed of active movements. These micro-organisms consist of a delicate protoplasm or vegetable albumen contained in a dense, resisting membrane containing cellulose. In some, colouring matter is found in this membrane and also, though much less frequently, in the protoplasm itself. This may give rise to colouration, which is visible to the naked eye. Under ordinary circum- stances, however, the protoplasm is colourless, or faintly yellow, and either homogeneous or granular in appearance. In order that they may live and grow, the micro-organisms require suitable food. Some of them grow and flourish in proteid or alt:)uminous substances; others again appear to require carbo-hydrates, and all retjuire a free supply of water, without which they cannot grow. Some grow best with a sup|)ly of free oxygen, and these are termed ' aerobic ' ; whilst others require that free o.xygen—that is to say, air—should be rigidly excluded. What small amount of oxygen they require, they obtain from the organic compounds in which they grow. These are termed ' anaerobic' Some, as we have seen, are capable of living and growing on dead animal matter ; they have therefore received the name of saprophytic fun^^i : others attack living tissues and can grow only on or in the animal body, like true parasites : these are there- fore Itxmci^ parasitic fungi. Some of these have never been cultivated outside the body, whilst others, though usually living outside the body, are capable of growing in it and setting up certain definite pathogenic conditions. For the most part micro-organisms develop and grow most readily at about the temperature of 95° F. ; but they may still continue to grow with a diminution of their functional activity within certain limits of temperature. It may be stated generally that bacteria cease to grow at a higher temperature than 105° F. or a lower temperature than 80- F. Heat is the surest and quickest method of killing bacteria ; some spores are killed in a few minutes in water at the temperature of 212^ F., and moist heat kills more rapidly than dry heat. Direct sunlight also retards their growth and may kill them. The most important point in connection with the growth of these micro- organisms is the power they possess of producing certain chemical com- pounds, which are termed ' toxines' and which are really the noxious elements. We have already seen that this is the case with regard to putrefaction, where it was stated that it was not the bacteria, the cause of the fermentation which set up the inflammation, but the chemical products (ptomaines) resulting from the growth of the organisms. It is in con- sequence of this fact that, though the lesion, the original source of the condition, is strictly localised, and therefore the region permeated by the micro-organism may be also strictly localised, still the most profound con- stitutional effects may be produced by the formation of these toxines, which, being exceedingly soluble, are carried to all parts of the body in the blood. Bacteria are very widely distributed. They are ])resent in the air, but not in the (juantities which it was formerly supposed ; for it is only those which can survive the absence of moisture and are adherent to particles of dust which can be carried in this way. I^ doubt in those places where bacteria are being generated in vast quantities a large number may be found circulating in the air. Sims Woodhead has shown that the tubercle bacillus was present in large numbers in the air of a room in which a considerable number of tuberculous animals were confined. And no doubt in a hospital ward containing a number of patients with wounds in a state of suppuration or decomposition we should expect to find a](https://iiif.wellcomecollection.org/image/b21210846_0048.jp2/full/800%2C/0/default.jpg)
