BACILLUS DIPHTHERIA 581 



consisting of 1 c.c. each of a toxin-antitoxin mixture so balanced that 

 there were about 4L+ doses per cubic centimeter, and that the mix- 

 ture contained about 85 per cent of an L+ dose per unit of antitoxin. 

 They added to these doses a billion killed diphtheria bacilli in order to 

 produce a certain degree of anti-bacterial immunity. With such treat- 

 ment Schick reactions could be rendered negative within a period of a 

 few months. A few individuals did not seem to respond by the devel- 

 opment of antitoxin and remained Schick positive. 



Recently, the method has been much perfected and it is being inten- 

 sively studied by Park and his force of workers at the present time. The 

 mixtures as recommended at the present writing are such that each 

 human dose of 1 c.c. contains at least 3L+ doses of toxin, so neu- 

 tralized with antitoxin that 5 human doses (5 c.c.) injected into a 

 guinea pig of 300 grams permits survival for at least fourteen or fifteen 

 days, but causes paralysis and death thereafter, while 1 e.c. of the 

 actual human dose produced no ill effects. From Drs. Krumwiede and 

 Banzhof, we have the details of the N. Y. Health Department require- 

 ments which have been accepted by the United States Public Health 

 Department as standards at the present moment. It must not be 

 forgotten, however, that by the time this book appears slight changes 

 may have been made since we are awaiting the publication of recent 

 studies from the Department of Health. 



We are indebted to the Director of the Hygienic Laboratory of the 

 United States Public Health Service in Washington, Dr. George W. 

 McCoy, for the following suggestions issued by the Public Health 

 Service. We include these matters because accidents have occurred 

 of recent years by mistakes in the preparation of the mixtures and even 

 deaths have been recorded. We take from the memorandum sent us 

 by Dr. McCoy, the following: 



The toxin and antitoxin used should be at least three months old 

 from the date of planting and date of bleeding, respectively. The L-h 

 doses have been found with reference to the United States standard 

 antitoxin. The unitage of the antitoxin to be used should be deter- 

 mined against this toxin so that one unit of the antitoxin to be used, 

 when mixed with the L-f dose of this toxin should permit survival for 

 ninety-six hours of 25 per cent of the guinea pigs injected. When a 

 tentative mixture of the product has been made, no further toxin shall 

 be added. Changes made should consist not in the addition of toxin, 

 but in the reduction of toxicity by the addition of antitoxin, if necessary. 

 Approximately one unit of antitoxin is, therefore, added to start with, 



