Читать книгу The Body at Work: A Treatise on the Principles of Physiology онлайн

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Not only has protoplasm the power of meeting with an antiferment any ferment which might prove prejudicial to its own integrity; but after it has been once attacked it continues to defend the vulnerable spot. Its tactics are, it must be confessed, somewhat like those of the dusky warrior who, during his first lessons in the art of boxing, made a point of covering with his fist the place where he had just been hit; but even its power of remembering its last injury is of supreme value to the human race. Before the age of sanitary science, and even, in certain backward communities, in these days of its beneficent rule, conditions producing disease were not necessarily set right as soon as the epidemic was over. The close-packed inhabitants of a ghetto were continuously exposed to germs of typhoid fever, small-pox, whooping-cough. But after their protoplasm had once responded to the need for the production of an antigerm, it either continued for many years to keep a stock in hand, or it kept the recipe within easy reach. The memory of protoplasm is amazing. It is commonly said that vaccination is an absolute protection for seven years. There is no doubt but that the immunity from small-pox which it induces, if gradually lessening, lasts for life. The disease, if it attacks a person who has been vaccinated in infancy, is relatively harmless.