. Animal biology. Biology; Zoology; Physiology. BIOLOGY AND HUMAN WELFARE 407 there is any relation between the disease of the Rat and of Man, and found that Man is infected with the plague bacillus, Bacillus pestis, by being bitten by a Flea from an infected rat. Extermina- tion of rats and fleas means the practical eradication of the disease, but in California the Ground Squirrels have become infected with the bacillus so the problem has become somewhat greater. Ru- bonic plague is doomed, though it has already taken an incalculable toll of human lives: even during the first four years of th
. Animal biology. Biology; Zoology; Physiology. BIOLOGY AND HUMAN WELFARE 407 there is any relation between the disease of the Rat and of Man, and found that Man is infected with the plague bacillus, Bacillus pestis, by being bitten by a Flea from an infected rat. Extermina- tion of rats and fleas means the practical eradication of the disease, but in California the Ground Squirrels have become infected with the bacillus so the problem has become somewhat greater. Ru- bonic plague is doomed, though it has already taken an incalculable toll of human lives: even during the first four years of the present century it destroyed about two million people in India. Still more recently San Francisco has been fighting an outbreak of the. Eggs Larva Pupa Adult Fig. 258. — Life history of the House Fly, Musca domestica. plague that not long ago would have been a national calamity; but it was immediately stamped out with the loss of compara- tively few lives. In brief, numerous parasitic Insects not only actually develop at the expense of animal tissue, but others act as the transmitting agents of Racteria, Protozoa, etc., which are the actual parasites,as we have already seen in the case of malaria, yellow fever, and Afri- can sleeping sickness. And last, but not least, we know that House Flies, which we tolerate as uninvited guests at our tables, have been shown to carry the germs of typhoid fever, tuberculosis, dysentery, and several other scourges. (Figs. 224, 248, 258.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Woodruff, Lorande Loss, 1879-1947. New York The Macmillan company
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