. . ; ^*** -INTRODUCTION 



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under pathological circumstances lead to the formation of anti-infectious 

 bodies. In an analogous and no less ingenious manner, Metchnikoff has 

 shown that the same cell group of mesenchymal origin which the organism 

 stations against bacterial invasion has physiological and physio-patho- 

 logical functions to f ulfill in the whole animal scale. In the lower animals, 

 these cells aid in the metamorphosis of the body structure, thus leading 

 to the disappearance of entire organs. In the female, they aid in the 

 involution of the uterus after labor, while in the aged they destroy the 

 nerve cells in the senile atrophied nerve centers or finally as chromophages 

 turn the hair gray. The border-line between the physiological and patho- 

 logical status is biologically not sharply demarcated. It is one single chain 

 of manifestations which possess numerous transitional phases. As the 

 methods of serum diagnosis can prove reactions much finer even than 

 those accomplished by chemistry, their application has not been limited 

 to the chapter on infectious diseases. 



By their means also, proteids, even though manifest in minutest traces, 

 can be differentiated. Similarly, the secret of blood relationship has 

 begun to be unravelled; and there is a possibility even of solving the 

 problems of metaboh'sm. 



Closely associated with serum diagnosis is the serum therapy. Even 

 though the general application of the latter is not as widely developed as 

 that of the former, it must be remembered that through this medium 

 diphtheria has been transformed from a fatal to a combatable disease, 

 and incidentally made the name of Behring immortal. To-day, attempts 

 are constantly being made to treat other bacterial and toxic diseases 

 by specific therapy and it is to be hoped that success will soon be met 

 with. 



The study of serum therapy and serum diagnosis is undertaken in 

 various ways. It is comparatively simple to learn only the purely 

 technical details. All large laboratories have trained assistants for the 

 performance of certain reactions or groups of reactions with absolute 

 precision. Although as we have said, they do such work as assigned to 

 them with accuracy, they are nevertheless far from a thorough understand- 

 ing of the subject of serum diagnosis. Unfortunately this blind method 

 of procedure has recently been advocated to an alarming extent. In 

 addition, the practical success which the Wassermann reaction has met 

 with has inculcated the desire in a certain class of physicians, for 

 carrying out this test alone, and thus to become independent of the 

 use of large laboratories. To meet this demand, short courses have been 

 established and the serum diagnosis of syphilis taught with lightning 

 rapidity. That such a state of events is absolutely injurious is clearly 

 evident. It is impossible for one to be a specialist in a certain reaction 

 and at the same time be ignorant of the other phases in the study of 



