MICROBIC DISEASES 227 



unknown. Thus when I was a boy in India, troops were marched 

 across the wind to new camps in the endeavour to avoid cholera. At 

 the present day even school children have some idea of the agencies 

 which cause them. Sanitary authorities work with a knowledge 

 of cause and effect, which is daily growing more exact, and hardly 

 a year passes but some disease hitherto mysterious is traced to a 

 microbic origin. As a consequence, both the prevention and treat- 

 ment of disease are becoming more rational. Men hope with good 

 reason to utterly abolish such terrible maladies as malaria, the 

 treatment of which was formerly limited to attempts to cure, and 

 which were supposed to be as irremovable a part of the natural 

 features of a country as its mountains and rivers. 



376. Human zymotic, infectious, or microbic diseases tuber- 

 culosis, scrofula, lupus, influenza, measles, common cold, bronchitis, 1 

 chicken-pox, smallpox, syphilis (great pox), and other venereal 

 diseases, whooping-cough, diphtheria, pneumonia, rabies (hydro- 

 phobia), tetanus (lock-jaw), enteric fever (typhoid), scarlet fever 

 (scarlatina), typhus, leprosy, septicaemia, peritonitis, malaria, 

 dysentery, epidemic diarrhoea, cholera, yellow fever, plague, sleep- 

 ing-sickness, erysipelas, rheumatic fever, puerperal fever, abscess, 

 meningitis, cerebro-spinal (spotted) fever, mumps, opthalmia, 

 phlebitis, tonsilitis (quinsy), beriberi, dengue, blackwater fever, 

 Malta fever, and a host of others are caused by the invasion of 

 the body of man, and the multiplication within his blood or 

 tissues of various species of microbes, minute unicellular plants 

 or animals, which find their nutriment in him. Very many of 

 these parasitic disease-producing (pathogenic) organisms have 

 been seen under the microscope. In many cases the causal con- 

 nexion of a species with the disease to which it gives rise has 

 been demonstrated by an experimental inoculation of non-infected 

 animals, and at the present day the doubts of a medical man as to 

 the nature of the disease he is treating are often solved by the 

 bacteriologist with his test-tube and microscope. 



377. Some zymotic diseases are comparatively rare. The 

 microbes may be uncommon, as those of spotted fever ; or they may 

 not easily find entrance into the living body, as those of lock-jaw, 

 or they do not readily establish themselves in the healthy tissues of 

 the normal individual, as those of septicaemia. Others are so 

 prevalent in some countries, and gain entrance to the body so 

 readily that no man escapes infection unless he is " by nature " 



1 See The Sixty-eighth Report of the Registrar General of Births, Deaths and 

 Marriages, p. cxiii. 



