The practice of surgery : a treatise on surgery for the use of practitioners and students / by Henry R. Wharton and B. Farquhar Curtis.

Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: The practice of surgery : a treatise on surgery for the use of practitioners and students / by Henry R. Wharton and B. Farquhar Curtis. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    tables, and must, therefore, be provided with the higher nitrogenous com- pounds, such as are produced by vegetable aud animal life. Some of them are able to live upon dead organic matter, while others cannot exist with- out liviug tissues to feed upon, and are, therefore, true parasites. There are some which are able to live either on dead or on living tissues, and they are known as facultative parasites, a class which includes the majority of pathogenic germs. Effect of Oxygen.—The germs require carbon and water as well as nitrogen, and some also need free oxygen, but to others this is not absolutely necessary, and there are some which cannot grow in the presence of free oxygen. Those which require oxygen are called aerobic; those which do not, anaerobic ; and the intermediate class, including most of the pathogenic varieties, are called facultative anaerobic, as they grow either with or with- out oxygen. Bacteria are very sensitive to temperature, few being able to live below 68° F. (20° C.) or above 104° F. (40° C), and the pathogenic varieties thrive best at about the normal temperature of the blood. Direct sunlight retards their growth, and may kill them. Growth. Spores.—Bacteria multiply by division, each cell dividing into two, which then grow as separate individuals, although they may remain connected in chains or clumps. A number of cells together sometimes throw out a gelatinous material which binds them into one mass, called a zooglcea. Some of the bacteria also grow by the production of spores, which are endo- genic or arthrogenic. The endogenic spores appear as minute round or oval bodies in the centre or at one end of the bacillus, which is usually distended by the growth of the spore. The parent dies, and the spore is set free. Under favorable con- ditions the latter will germinate, but if the proper soil or food and tem- perature are not at hand, it remains quiescent, like the seed of a plant, waiting, it may be for years, until proper conditions are present. The spores have such a thick envelope and such great vitality that it is much more difficult to kill them than the developed cell, a temperature of 212° F. (100° C.) moist heat being required to destroy the spores of anthrax, for instance, whereas 130° F. (55° C.) will kill the bacillus. The arthrospores are not so resistant. The cocci never produce endogenic spores, but are limited to the arthrospores, while the latter are rarer in the bacilli. But little is known of the arthrospores, and they appear to be simply larger and more resistant than the ordinary individual cocci. The growth of spores is a sign of deterioration of the bacteria, for, while other fungi produce spores under any conditions, the bacteria grow by division so long as the conditions are favorable ; and it is only when a lack of food- material, a change in temperature, or an accumulation of their own poisonous products threatens them with extinction that the more resisting form, the spore, is produced. Toxines.—As bacteria grow, certain poisonous chemical substances appear about them, either produced by them directly, like the excretory matters of other plants, or formed in the organic matter or tissues in which they live as a result of their presence. Some of these substances are alka- loidal, and are known as ferments or ptomaines, while others are albuminous
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