MAN'S FIGHT FOR SURVIVAL 623 



It might be thought that with all of these bacterial foes and so 

 many means of infection the human body would succumb without 

 even making a fight. However, man has several definite ways of 

 resistance. In the first place a good state of health does much to 

 give effective resistance to entering bacteria. The skin, if healthy, 

 is an effective barrier and is far more effective if it has no abrasions. 

 Many secretions given off from the protective tissues, such as tears 

 which cover the conjunctiva of the eye, the various juices of the 

 digestive tract, and even the lymph that surrounds the body cells, 

 contain resistive substances that prevent the growth of bacteria, pro- 

 vided the body is in a healthy condition. 



Some Important Bacterial Diseases 



Although modern medicine is rapidly conquering many diseases, 

 some still remain unvanquished. Of these, tuberculosis stands out 

 as one of the most serious enemies of man. While the common cold 

 causes more days of illness and is perhaps economically the most 

 important, it is not as serious a menace as tuberculosis, which is 

 probably responsible for one tenth of all the deaths due to diseases 

 to which man is subject. In 1900, the death rate from tuberculosis 

 was 195.2 for each 100,000 inhabitants in the registered area of the 

 United States. In 1935, the death rate in the same area had dropped 

 to 51.2 per 100,000. While this is encouraging in the extreme, it does 

 not mean that the disease is conquered. 



Tuberculosis is caused by the growth of tubercle bacilli within the 

 lungs or other tissues of the body. In the lungs they form small 

 tubercles which close up the delicate air passages, while they also 

 attack other parts of the body, causing tuberculosis of the bones, 

 scrofula, and other diseases. Tuberculosis is usually contracted from 

 other people who have the disease, although in the case of children 

 the bovine tuberculosis germ may cause the disease. Dr. William H. 

 Park, a noted authority on bovine tuberculosis, states that in a very 

 large number of cases investigated, 57 per cent of abdominal tubercu- 

 losis in young children and 47 per cent of such tuberculosis in children 

 under five years of age was of the bovine type. It is needless to say 

 that all milk should come from tuberculin-tested cows or at least be 

 pasteurized, especially if the milk is of doubtful origin, since this 

 method, if properly used, will kill the tuberculosis germs. About 

 one per cent of the beef cattle show tuberculosis by test, but the 

 meat from such cattle, if properly cooked, is not a menace. 



