Medical Diagnosis. 17 



actual structural lesions and disorders of function should be 

 thoroughly investigated. As supplementary to the more promi- 

 nent objective symptoms any fever or other constitutional disorder 

 must be sought for ; a mental list must be made of the diseases 

 which resemble this one, and these must be excluded one by one 

 by careful attention to the differential symptoms ; other diseases 

 which are probably subsidiary to this, should be similarly investi- 

 gated and excluded ; any really diagnostic sign of the suspected 

 disease must be carefully established and the diagnosis finally 

 placed on a solid foundation. The discovery of a constitutional 

 (febrile) disease to which a distinctive name can be given is by 

 no means the end of the diagnosis ; the structural lesions of the 

 disease may be largely localized in an unimportant organ where 

 they may remain circumscribed without compromising life, or 

 they may be seated in a vital organ which will render the disease 

 grave to the last degree or necessarily fatal. For example : An- 

 thrax of a dense, dry part of the skin may be a mild local disease ; 

 anthrax of an internal organ is usually fatal. Every local com- 

 plication therefore, should be as carefully diagnosed as the con- 

 nected constitutional disorder. 



But diagnosis cannot always be certain. In the early stages of 

 certain fevers two different forms may be as yet indistinguishable 

 and a day or two may be required to develop differential symptoms. 

 In some occult forms of disease all differential symptoms may fail 

 us. A method of diagnosis which has hitherto been applied only 

 to tuberculosis and glanders is manifestly capable of much wider 

 application, to diseases attended with a febrile reaction. This 

 consists in a hjrpodermic injection of a minimum dose of the ster- 

 ilized and filtered products of the culture of the disease germ, 

 which produces no effect on the healthy system but causes febrile 

 reaction or local inflammation, or both, in the diseased. This will 

 be treated more fully under the respective diseases. 



In connection with such a method, but above all when no such 

 resort has been had, the obscure case should be seen frequently, 

 the course, duration, and termination of the disease should be 

 noted, also its tendency — sporadic or epizootic, and finally the 

 result of treatment. This last resort may often secure diagnosis 

 and cure at once, as when a course of iodine cures an obscure ac- 

 tinomycosis. 



