INTRODUCTION. 5 



agencies no longer act. In the diagnosis of disease 

 COMPLICATION is an important element. As a rule, we have 

 to do with disease of more parts than one, and have to 

 come to a clear understanding in each case, for the dis- 

 ease which causes the others, the peimary disorder, must 

 be that against which our medicinal efforts are directed. 

 If we succeed in removing it, secondary diseases result- 

 ing from it will generally disappear. Thus, dropsy is a 

 secondary condition often dependent on heart disease. 

 Secondary pathological conditions may be due to co- 

 operation in function, or to continuity or contiguity of 

 structure. The instance just given illustrates the first 

 method, for the dropsy results from escape of watery con- 

 stituents through the walls of the overloaded vessels which 

 cannot perfectly pour their contents into the heart. Ex- 

 tension by continuity of structure is seen when the pleura 

 becomes involved by extension of disease which originated 

 in the lungs. Contiguity is less frequently a means of 

 spread ; sometimes we see a gangrenous patch on the 

 wall of a serous cavity opposite a gangrenous portion of 

 a contained viscus. This means is also exemplified in joint 

 diseases, and wherever living cells lie together without or- 

 ganic connection. Occasionally we find in a special disease 

 some symptoms by means of which its nature may be at 

 once determined; such a symptom is termed Pathognomonic. 

 Thus, the presence of the anthrax Bacillus in the blood is 

 pathognomonic of charbon, and the changed condition of 

 the urine similarly enables us at once to determine the 

 presence of hsBmo-albuminuria. 



The History of every case of disease should be ascer- 

 tained with the utmost care, and when possible a written 

 record should be kept for future reference. It should 

 comprise all ascertained particulars of the case, from its 

 commencement to its termination. It will prove not only 

 a more sure guide to diagnosis and prognosis than the 

 memory, but will enable the practitioner to perform his 

 duty to the profession in recording the case if it prove 

 interesting. We can never be assured of the professional 

 value of a case until it has terminated. Much of the 



