uS THE POPULAR SCIENCE MONTHLY 



therapeutics and serum-diagnosis and by the extension of the idea of 

 preventive inoculation. As may readily be seen, the fundamental ob- 

 servations of Pasteur, of Behring and of Pfeiffer had been elaborated 

 into some of the most serviceable principles, acknowledged at the mo- 

 ment, in the science and practise of medicine. Nor is this influence a 

 matter of the past. In our own day has been established the theory of 

 specific precipitation of foreign proteins (Uhlenhuth, 1901). This has 

 led to the elaboration of a specific test for the differentiation of both 

 vegetable and animal proteins, a method which has been adopted for 

 the determination of species, not only in bacteriology, but also as a 

 medico-legal test for determining the origin of blood stains and as a 

 general biological procedure. 



So also, through the work of Denys and later of A. E. Wright, a 

 body has been recognized in the serum which had the power to prepare 

 bacteria for ingestion and digestion by the leucocyte. To this body the 

 name of opsonin or tropin has been given. You will remember that 

 Metchnikoff discovered the fact that the white cells of the blood have 

 the power to engulf bacteria, Wright supplemented this conception of 

 demonstrating that a substance in the serum could so affect bacteria 

 that they would be taken up more readily and in greater numbers ; also 

 he demonstrated that this opsonic power of the serum could be in- 

 creased, and as the results of his teachings a definite opsonic therapy 

 has developed. This treatment depends on the principle of vaccination 

 with bacterial products. Before Wright, with the exception of Pas- 

 teur's treatment for hydrophobia, vaccination was used as a preventive 

 measure only, but the studies which his observations have stimulated 

 have led to very satisfactory results in the treatment of certain local 

 infections as those due to the pus cocci and colon bacillus. Also, 

 these studies have extended the practise of immunizing vaccination, as 

 a prophylactic measure with, it has been claimed, most favorable re- 

 sults in the prevention of typhoid fever. For example the sanitary 

 record of the maneuver division of the United States Army recently 

 stationed on the Mexican border shows that in a body of 8,097 enlisted 

 men, careful sanitation and antityphoid inoculation prevented almost 

 entirely the occurrence of typhoid fever; only one case of typhoid fever 

 was observed, and it was not fatal ; while at the same time in the near-by 

 city of San Antonio 49 cases were reported. Comparing the record of 

 the maneuver division with that of a division of the Seventh Army 

 Corps stationed at Jacksonville, under quite similar circumstances in 

 1898, we have one case of typhoid among the 8,097 men of the former 

 and 2,693 undoubted cases among the 10,759 men of the latter division. 

 It must be admitted in regard to this record of the maneuver division, 

 that it is difficult to say to what extent the excellent showing was due 

 to careful sanitation and to what extent to the antityphoid inoculation, 



