File:Biology and man (1944) (20383531465).jpg

Title: Biology and man
Identifier: biologyman00grue (find matches)
Year: 1944 (1940s)
Authors: Gruenberg, Benjamin C. (Benjamin Charles), 1875-1965; Bingham, N. Eldred (Nelson Eldred), 1901-
Subjects: Biology; Human beings
Publisher: Boston, New York, (etc. ) Ginn and company
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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Seed ticks THE TICK Young adult female Engorged adult female Female laying eggs Bureau of Entomology and Plant Quarantine. I .s.U.A. The tick is known to transmit Rocky AAountain fever, or spotted fever, among human beings. Another species transmits the Texas cattle-fever, which was formerly a very expensive scourge in this country. (The ovipositor, on the abdomen, points forward behind the mouth, so that the discharged eggs spread all around the female's head) How Do People Become Infected? Communicable Diseases Following the methods and the principles developed by Koch, investigators have identified the specific parasites causing some of the most important human diseases, such as tuberculosis, diphtheria, syphilis, typhoid fever, tetanus, pneumonia, malaria, gonorrhea, Asiatic chol- era, bubonic plague and hookworm. These diseases are important because they have again and again killed from a tenth to nearly half the population in great plagues or epidemics. And without flaring up into plagues they have been the greatest causes of deaths, year in and year out, in many regions. Common observation and countless experiments with plants and animals leave us certain that the communicable diseases are caused by parasites or viruses. And that they are communicated by the entrance of something mate- rial into the body—either through one of the regular openings to the interior, as the mouth, nose, or urethra, or else through a cut or break in the skin. Wounds and Germs For ages common experience had recognized the general fact that wounds fester. Nobody knew why; nor why some festering, or pus-making, ended in healing, whereas other festering was fatal. That is the way wounds act. Whether the skin is broken by a gunshot, a jagged rock, or a surgeon's knife, the two possibilities are present. In hospitals it had been observed that however skillful a surgeon might be, his patients often died as a result of the festering, or "blood-poisoning" as it was called. There was also an excessive number of maternal deaths associated with fever and blood- poisoning. And nobody knew why, nor what to do about it. 617

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