422 MICROORGANISMS 



486. Former Theories of Disease. Before taking up a 

 discussion of the nature of bacterial diseases, it might be well 

 to consider briefly some of the early theories that have been 

 held concerning the cause of disease. One of the earliest of 

 these theories consisted in a belief that the diseases were 

 caused by an "evil spirit" which entered into the body and 

 behaved in such a manner as to bring pain and suffering to 

 the patient. Such a theory was more or less of a natural 

 inference from a superficial study of the symptoms of an 

 ordinary disease, and it seemed to fit particularly well as the 

 explanation of the various forms of diseased condition which 

 we know as insanity. This theory was held longest in regard 

 to diseases of this type. 



Two different lines of treatment were followed in attempt- 

 ing to cure diseases according to this theory. It was thought 

 that the spirit could either be induced to leave the body of 

 the patient by sacrifices or promises or it could be forced to 

 leave by charms, by the beating of tom-toms, or by torturing 

 the body of the patient, and thus making it uncomfortable for 

 the intruder. You have doubtless read of some of the strange 

 customs practised by savage tribes today in the treatment of 

 their sick. Most such customs grow out of some form of 

 this theory of disease, for it seems that most present-day 

 primitive peoples, as well as the savage ancestors of civilized 

 man, hold to this theory in some form. 



487. Semi-scientific Theory of Disease. Hippocrates, a 

 Greek philosopher, who was born about 460 B. C. and who is 

 often called the "Father of Medicine," promulgated a new 

 and semi-scientific theory of disease. According to this 

 celebrated theory, the body contains four humors: blood, 

 phlegm, yellow bile, and black bile. Health consisted of a 

 proper mixture of these four humors and disease consisted of 

 an improper mixture. The treatment of diseases according 

 to this theory, consisted in an effort to keep the humors in a 

 proper relation to one another. This was done by administer- 

 ing powerful drugs. This theory soon gained world wide 



