450 



INFECTION AND RESISTANCE 



paralysis may follow even when vigorous serum treatment has been 

 employed. For, according to them, only the toxin which has reached 

 the central nervous system through the circulation can be influenced 

 by the serum, but no effect is possible upon the fraction which has 

 been absorbed from the nerve endings directly. 



Schick, 6 on the basis of extensive experiments, comes to the con- 

 clusion that the subcutaneous injection of 1,000 to 2,000 units in 

 diphtheritic cases has an immunizing value only, which protects the 

 tissues from further injury and leads to cure if, at the time of injec- 

 tion, the lethal dose has not yet united with the sensitive cells. "If," 

 he states, "we wish to obtain antitoxic action upon toxin which has 

 already gone into action before the injection of the serum, then re- 

 sults can be obtained both in man and in animals only if a great deal 

 of antitoxin is injected intramuscularly or intravenously." 7 



Interesting also from a clinical point of view are the studies of 

 Schick, 8 Hahn, 9 and others 10 upon the presence of antitoxin in the 

 blood of normal, untreated individuals at different ages. These 

 investigations were carried out by the intracutaneous method of 

 toxin and antitoxin determination described in greater detail in a 

 later section. The following table, taken from the article of Hahn, 

 illustrates the experience, in such investigations, both of Schick and 

 of Hahn himself. The determinations were carried out upon indi- 

 viduals who had never had diphtheria, as far as could be learned. 



The table shows that in newborn children there is almost regu- 

 larly a definite and sufficient protective value in the serum which 

 diminishes up to the first year, so that at the end of the first year 

 three out of four individuals had no antitoxin in their serum. In 

 subsequent years up to the age of 40 an increasing percentage of 



6 Schick. Loc. cit. 



7 Schick. Loc. cit., p. 32. 



8 Schick. "Uber Diphtherimmunitat," Wiesbaden, 1910. 



9 Hahn. Deutsche med. Woch., Vol. 38, No. 29, p. 1366, 1912. 



10 Karasawa and Schick. Zeitschr. f. Kinderkrankheiten, 1910, and " Jahr- 

 buch f. Kinderheilkunde," 1910. 



11 Table taken directly from Hahn, loc. cit. 



