X PREFACE TO THE THIRD EDITION 



pregnancy, were published. Pregnancy is a con- 

 dition which allows of no misinterpretation. In 

 almost every case the clinical diagnosis can be 

 compared, with absolute certainty, with the result of 

 the serological diagnosis. The actual diagnosis 

 either corresponds with the former, or it does not. 

 These clear conditions, however, are not presented by 

 the other morbid processes. A certain disease may 

 be accompanied by all kinds of other disturbances of 

 the functions of the organ. Very seldom are we faced 

 with the presence of " pure " disease. Therefore, we 

 are bound to conclude that only the worker in a 

 hospital is in a position to judge, to what extent sero- 

 logical investigations can be applied for testing the 

 functions of an organ. In this case two aims have to 

 be distinguished. The serological diagnosis can, in 

 many cases, widen our understanding of the disturb- 

 ances occurring in a given disease. We gain an in- 

 sight into long suspected functional troubles of certain 

 organs, or discover that others, which had never 

 been thought of, regularly produce disturbances in 

 a certain disease. It is an entirely different question 

 to ask whether the serological diagnosis of an organ 

 can be applied to differential diagnosis, i.e., whether 

 we are entitled to accord a preference to this, as 

 against any other, method. 



Many years may be required before the question 

 of the practical value of the methods worked out can 



