296 Microbes and You 



walk under a ladder, or that person whose path is crossed by a 

 black cat. Biblical writings give references to "those who are 

 possessed." While the methods employed for removing evil spirits 

 make interesting reading, there is little that is scientific in the 

 procedure. 



THE MIASMIC THEORY OF DISEASE 

 The observation was made in years gone by that persons who 

 lived in areas abounding with swamps and bogs appeared to have 

 a disproportionate amount of illness. Polluting agents in the 

 vapors, or miasmas, were believed to be the cause of the sickness. 

 Miasma is a word of Greek origin and means defilement, and such 

 emanations from swamplands defiled the atmosphere, according to 

 popular notion. A direct carry-over from this era is the word 

 malaria, which means bad air. What more proof did anyone need 

 than the observation that those who worked in sewers contracted 

 severe chills and fever which might last for prolonged periods? 

 The misnomer, malaria, has persisted through the years, even 

 though we know that even in the finest air-conditioned atmosphere, 

 a person may contract malaria if the right species of an infected 

 female anopheline mosquito bites a susceptible individual. It just 

 so happened that the sewers provided the breeding ground for such 

 mosquitoes, with the foulness of the air being an unrelated con- 

 comitant factor. It is so easy to draw hasty conclusions in science! 



THE HUMORAL THEORY OF DISEASE 

 Hippocrates (460-395 B.C.) believed that a harmonious relation- 

 ship between the four humors of the body— phlegm, blood, yellow 

 bile, and black bile— was essential if a person was to remain in a 

 healthy condition. When any one or more of these humors got 

 out of balance with the others, disease was the expected alternative. 

 Blood-letting as a means of restoring the proper balance between 

 the humors was commonly practiced in the United States at the 

 time of George Washington. A carry-over of this theory of disease 

 is found in such common non-medical expressions as sanguine, de- 

 noting too much blood and a confident, and hopeful attitude. 

 Melancholy is derived from black bile, indicating a state of low 



