July 28, 1916] 



SCIENCE 



113 



turned over and asks himself what use he 

 can make of it. 



Let me illustrate the stages in the evolu- 

 tion of modern medical science from med- 

 ical art by an outline of the development of 

 our useful knowledge in respect to a single 

 disease, namely, typhoid fever. 



Typhoid fever has been, and still re- 

 mains, one of the significant causes of death 

 and disability. So far as can be shown from 

 the necessarily incomplete statistics of the 

 Public Health Service, there were over 17,- 

 000 deaths from this disease in the United 

 States in 1913, which means there were 

 over 170,000 cases, since the mortality aver- 

 ages ten per cent. It is a malady partic- 

 ularly prevalent in crowded groups of men, 

 such as armies and asylums. Sixty per 

 cent, of all the deaths in the Franco-Prus- 

 sian War were due to typhoid, and in the 

 Spanish-American "War one fifth of all the 

 enlisted men contracted the disease, and 

 there were seven times as many deaths 

 from it as from implements of war. And 

 typhoid fever is important not only as a 

 cause of death, but particularly owing to 

 its economic waste; for an acute disease it 

 has a particularly lengthened course and is 

 followed by frequent sequels. It has re- 

 cently been estimated that the economic loss 

 in this country from typhoid is $50,000,000 

 annually, as a disease ranking second only 

 to tuberculosis. 



Our interest in typhoid fever is height- 

 ened by the fact that it is not only an im- 

 portant disease, but one which can and will 

 eventually be obliterated. Recent reports 

 from the Surgeon-General of the United 

 States Public Health Service show that the 

 incidence of this disease is probably not 

 more than half what it was thirty years ago, 

 owing in large part to improved sanitation 

 alone. 



Perhaps the one most significant line of 

 advance in medicine has been the gradual 



recognition of disease entities. On the rec- 

 ognition of separate diseases depends all 

 measures of quarantine, prevention and ra- 

 tional therapy. Diagnosis, the recognition 

 of a disease entity, depends on the patient's 

 symptoms and these symptoms are of two 

 classes; subjective, or those the patient him- 

 self experiences as pain, chilliness, and the 

 like; and objective symptoms which the 

 physician can detect. Among the latter 

 may be mentioned rapidity of the heart- 

 beat, fever, eruptions, changes in blood 

 pressure; changes in the blood and urine, 

 and the like. Medical progress has been 

 dependent on the methods of recognizing 

 such constant variations from the normal 

 as are found characteristic of a given type 

 of disease. Such variations were detected 

 at first by the unaided powers of observa- 

 tion, and later by the employment of instru- 

 ments and methods of precision introduced 

 in the evolution of the medical sciences. 



One of the most important symptoms of 

 the parasitic or infectious diseases is a rise 

 in bodily temperature, or fever. A fever 

 is a disease characterized by such a rise in 

 temperature and some fevers continue over 

 a period of days or weeks. The disease we 

 now recognize as typhoid or enteric fever 

 is one of these continued fevers and, al- 

 though probably seen by Hippocrates, was 

 for centuries confused with other lasting 

 fevers of somewhat similar appearance. 

 Recurrent fever, septic infections, and 

 typhus fever in particular present pic- 

 tures which even to-day in their beginnings 

 and in their purely clinical aspects may be 

 confused with typhoid. 



"We owe our first full description of what 

 was probably typhoid fever to an English 

 physician, Thomas Willis, who in 1643 de- 

 scribed an epidemic of the disease that oc- 

 curred in the Parliamentary troops. Early 

 in the eighteenth century Strother, another 

 Englishman, described ulcerations in the 



