BACTERIACE.E : THE BACILLUS OF DIPHTHERIA 293 



was found to be capable of neutralizing the poisonous property 

 of diphtheria toxin. The brilliant success of Roux (1884) in treat- 

 ing diphtheria with antitoxic serum caused the rapid adoption' 

 of antitoxin as a therapeutic agent throughout the world. Park 

 and his co-workers, Atkinson, Gibson and Banzhaf, have devel- 

 oped a method of concentrating diphtheria antitoxin which is 

 now generally employed. 



For the production of antitoxin 1 young healthy horses are 

 selected with great care. They are specifically tested for tubercu- 

 losis and glanders. A powerful diphtheria toxin is then injected 

 into the horses, in an amount sufficient to kill 5000 guinea-pigs, 

 together with 10,000 units of antitoxic serum. The toxin is 

 subsequently injected at intervals of three days and each succeeding 

 dose is increased by about 20 per cent as long as the condition 

 of the horse is satisfactory. At the end of two months the dose 

 is about fifty times as large as the initial dose. Antitoxin is 

 given only at the start. The serum of the horse is tested from 

 time to time and, when the desired antitoxic strength has devel- 

 oped, the blood is drawn once a week for the preparation of anti- 

 toxin. A dose of toxin is given after each weekly bleeding. 

 The blood is drawn from the jugular vein into jars containing a 

 10 per cent solution of sodium citrate, nine parts of blood to one 

 of the citrate solution. The material is mixed and allowed to 

 sediment in a refrigerator. The plasma is then siphoned off 

 into large bottles and heated to 57 C. for 18 hours to change 

 part of the soluble globulins 2 to euglobulins, insoluble in a satu- 

 rated solution of sodium chloride. An equal volume of saturated 

 aqueous solution of ammonium sulphate is then added. The 

 precipitate which forms consists of the globulins and nucleopro- 

 teins of the plasma. This precipitate is collected on a filter 

 and extracted with a saturated solution of sodium chloride, in 

 which the pseudoglobulin fraction, carrying with it the antitoxic 



1 For details of the method see Park and Williams, Pathogenic Bacteria and 

 Protozoa, Phila., 1910. 



2 Banzhaf: The Preparation of Antitoxin; Johns Hopkins Hosp. Bull., 1911, 

 Vol. XXII, pp. 106-109. 



