. Textbook of botany. Botany. 24 TEXTBOOK OF BOTANY. than in fresh air. Plenty of fresh air and sunshine are there- fore very important, and especially so in the house where a tuberculous person lives or has lived. It is in crowded, unventi- lated, and poorly lighted tene- ments that a large proportion of cases of tuberculosis occur, both because conditions there are more favorable for the bacteria, and because persons living under such conditions are less healthy and so less able to throw off the disease. 37. Diphtheria.—Thisiscaused by a bacterium, that finds lodg- ment in the throat (Fig. 9
. Textbook of botany. Botany. 24 TEXTBOOK OF BOTANY. than in fresh air. Plenty of fresh air and sunshine are there- fore very important, and especially so in the house where a tuberculous person lives or has lived. It is in crowded, unventi- lated, and poorly lighted tene- ments that a large proportion of cases of tuberculosis occur, both because conditions there are more favorable for the bacteria, and because persons living under such conditions are less healthy and so less able to throw off the disease. 37. Diphtheria.—Thisiscaused by a bacterium, that finds lodg- ment in the throat (Fig. 9, B). Living and multiplying here, the bacterium gives off a toxin which is carried by the blood to other parts of the body and there produces the serious symptoms of the disease. The presence of the toxin in the blood of the sufferer causes the blood to form an antitoxin — a sub- stance which counteracts the poisonous effects of the toxin. If the antitoxin is formed in large enough quantity, the most serious effects of the disease do not appear; the patient finally gets rid of the bacteria that are producing the poison and recovers. If the antitoxin is not formed rapidly enough, the disease grows worse and the patient dies. Fortunately it has been found that a horse or mule inoculated with diphtheria toxin produces a large amount of antitoxin, and that this antitoxin, taken from the animal and injected under the skin of the human sufferer, has the same effect as the human antitoxin. To be effective in curing diphtheria, the antitoxin must be given early in the course of the disease; so it is most im- FiG. 10. — Photograph show- ing the growth of bacterial colonies on an agar plate that had been exposed for a short time to the air. The bacteria floating about in the air settled upon the plate and there grew and Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1917
