22 THEORY OF MIASM 



form. With sound sense, the Greek Father of Medicine said that 

 when a large number of people fall ill simultaneously the cause must 

 be sought in that which is common to all, and what can that be save 

 the air they breathe ? It was observed, however, that while the whole 

 community was breathing the same air, many remained well ; some had 

 eruptive diseases; others diarrheal disturbances; and still others, res- 

 piratory affections. This necessitated the division of men into groups 

 according to temperament. With the same factor in the air the result 

 would vary with the temperament of the individual. 



The study of the cholera epidemics of the nineteenth century 

 removed the last scientific support of the theory of miasm. It had 

 long been a matter of observation and record that epidemics travel 

 from east to west. This was noted before the Christian era. It was 

 frequently observed in classical times, and the cholera pandemics gave 

 opportunity for collecting exact data on this matter. It was found 

 that cholera, which is endemic about the delta of the Ganges, becomes 

 pandemic on the occasion of certain religious pilgrimages. The faithful 

 followers of Mohammed from all points of the compass gather at 

 Mecca. Some come from the home of cholera, bringing the infection 

 in their bodies. From their discharges others become infected, and 

 as the great concourse disperses, bands of returning pilgrims carry the 

 infection with them, and the disease widens its area. It travels just 

 as fast and no faster than man travels. It goes where he carries it 

 and nowhere else. When an individual drops the infection, some one 

 else must pick it up and carry it on or it ceases to spread. The gen- 

 eral direction of the spread of infection has always been from east to 

 west because the great lines of human travel have led from this point 

 of the compass, but it was found in the study of the cholera epidemics 

 that whenever and wherever the paths of travel deviated from the 

 general direction, the infection showed the same deviation. In other 

 words, it became evident that infected man carried the infection in 

 his own body. However, when the pandemics spread over Europe it 

 was noticed that, while no place became infected unless visited by 

 some infected individual, the disease established itself in certain locali- 

 ties and failed to do so in other places. This observation gave some 

 support to the theory of miasm. In some soils the seeds of the disease 

 grew and multiplied while in others they did not. When the water- 



