EDWIN J. BANZHAF 747 



vidual hypersensitiveness to the proteins in the toxin dikition may be tested by. 

 means of a control outfit. For this test the toxin should be heated to 75° C. for ten 

 minutes, which destroys the action of the toxin but leaves unaltered the substances 

 causing the pseudo-reactions. 



Scarlatinal toxin. — The streptococcus scarlatinal toxin (Moser/ Gabritschewsky/ 

 Savchenko^) was used by the Dicks'' in a skin test to determine the presence or 

 absence of immunity to scarlet fever. They also corroborated the work of Savchenko 

 who found that the toxin, when injected in increasing amounts, actively immunized 

 individuals susceptible to scarlet fever. The technique used in making the Dick test 

 is identical with that used in the Schick test, with the exception that the result is 

 noted at the end of twenty-four hours. The reaction disappears in forty-eight to 

 seventy-two hours. A positive reaction consists of a reddish area from i to 3 cm. 

 As in the Schick test, a small percentage of pseudo-reactions occur due to the sus- 

 ceptibility of the individual to the protein substances in the toxin broth. The toxin 

 to be used as a control must be boiled two hours because it is very heat resistant. The 

 Dicks's-' standardization of the S.T.D. (skin-test dose) of the toxin is that amount of 

 toxin, which, when injected intracutaneously in non-immunes in a total volume of 

 yV mil, will cause a reaction of 1-2 cm. in diameter. The standardization presents 

 difficulties in that at the present time only non-immune human beings and a special 

 breed of rabbits and Swiss goats (Saaren) give a visible reaction (skin reaction) more 

 or less regularly. As a rule, the toxin is quite stable. The Dicks, A. W. Williams, 

 and others have prepared toxins that have retained the larger part of their toxic value 

 for years. The toxin prepared in media, without blood, usually contains about 

 20,000 S.T.D. 's to each mil. Highly diluted toxins may drop in their S.T.D. content 

 during the first month; after this time the toxin remains constant for at least six 

 months. The Dick-test toxin supplied to physicians is diluted so that each ^V n^il 

 contains i S.T.D. For the active immunization of individuals against scarlet fever 

 the Bureau of Laboratories of the Department of Health, City of New York, recom- 

 mends at the present time four injections subcutaneously at weekly intervals, the 

 following amounts of S.T.D. 's: first injections, 600; second, 2,400; third, 6,000; and 

 fourth, 12,000. 



The Dicks recommend larger doses of from 50,000 to 70,000 S.T.D. 's, divided in 

 five injections. However, at the present time our evidence shows that four injections 

 are sufficient to confer an immunity to a skin-test dose in about 80 per cent of the 

 individuals. The fifth injection of the Dicks might raise the immunity to 90 per 

 cent. Our method is to test by the Dick method one or more months after the fourth 

 injection and give to those that are still positive a second series of two injections of 

 about 10,000 and 20,000 S.T.D. 's. 



It should be emphasized that, when the Dick test is given to determine if active 

 immunity has resulted from this treatment, a control test of heated toxin should be 



'Moser: Wien. klin. Wchnschr., 15, 1053. 1902 



^ Gabritschewsky, G.N.: Ccntralbl.f. BaktcrioL, Orig. I, 41, 719. 1906; Bcrl. klin. Wchnschr., 44, 

 556. 1907. 



* Savchenko, J. G.: Russk. Vrach., 25, 797. 1905. 



^ Dick, G. F., and Gladys H.: J.A.M.A., 81, 1066. 1923; 83, 84. 1924. 



