LOCAL REACTIONS 8 1 



serum should be used in another experiment; an emulsion of staphylococci and 

 washed leucocytes being used as above. After pursuing the same steps in this 

 experiment as in the first, the average number of staphylococci per leucocyte 

 is determined. 



To obtain the opsonic index, it is necessary to know the ratio of staphylococci 

 in the leucocytes treated with the furuncular serum, and in the normal. If the 

 normal serum leucocytes contained 10 staphylococci, and the furuncular serum 

 contained 15, the index would be 1.5. 



In the case of tubercle bacilli, the latter must be heated to 100 C. to kill 

 them, otherwise they will be agglutinated by the serum, and a homogeneous 

 emulsion will not be obtained. After heating, the clumps must be broken up 

 by grinding the masses in an agate mortar, adding a little salt solution from 

 time to time until the mass is thoroughly broken up. The bacilli must then, 

 after phagocytosis, be stained by carbol fuchsin and decolorized with acid alcohol. 

 If the leucocytes are left too long in contact with the organisms they may become 

 so engorged as to prevent counting, the number increasing from 5.7 percent 

 after five minutes to 28.5 percent in two hours. 



Highly immunized anti-bacterial serums have much greater opsonic powers 

 than have normal ones, anti-streptococcus and anti-pneumococcus sera being 

 especially powerful toward streptococci and pneumococci. It is possible to 

 increase the opsonic powers of the blood of an individual suffering from an 

 infection, by vaccinating him with' killed cultures of the organism with which 

 he was infected. 



Wright has treated tubercular and septic infections in this way with excellent 

 results, the opsonic index of the individual being very markedly raised. Others 

 have not had such convincing results with the opsonic index. 



The Local Reactions or Tests. We have learned in the past few years 

 that the skin and mucous membranes will react more or less specifically 

 to the bacterial proteins. It is a form of allergic (see page 58). There have 

 been developed local tests for tuberculosis, syphilis, typhoid, glanders and other 

 diseases. The first two being the most important, are considered below. 

 The others are of similar nature. 



Tuberculosis. If tuberculin of any form be rubbed into an abraded skin 

 area or injected between the layers of the skin a red maculopapule or even vesicle 

 upon an inflamed base will appear within 24 hours. There may be a mild general 

 reaction of fever and malaise. A positive reaction to such an installation simply 

 indicates the presence of a tuberculous lesion and that an anaphylactic state 

 of the skin exists but does not show whether or not the lesion is active. For this 

 reason it is only of value in children since three-fourths of adults are believed 

 to have a healed lesion within them. Not only upon the skin but upon the 



