Part VI. 
COMPARATIVE TOXICITY OF UNTREATED AND REFINED 
ANTITOXIC SERUM. 
It has long been known that diphtheria antitoxin is precipitated 
from the serum with the globulins, and many attempts have been made 
to separate the antitoxin from the nonantitoxic substances contained 
in the serum. 
Gibson " has evolved a practical method of concentrating and refin- 
ing diphtheria antitoxic serum. Part of the process consists in placing 
the one-half saturation of ammonium sulphate precipitate derived from 
the antitoxic serum in saturated sodium chlorid solution. This dissolves 
a portion of the globulins with all tne antitoxin. In this way the nucleo- 
proteids and insoluble globulins present in the first precipitate are 
eliminated. The soluble globulins are precipitated by acetic acid, 
filtered, partially dried, and finalh^ placed in a sack of parchment 
membrane and dialyzed in running water. This antitoxic solution of 
soluble globulins is then rendered neutral and sufficient sodium chlorid 
added to make it isotonic. 
Park and Throne^ find, from a comparative study of 100 cases, that 
the removal of a considerable portion of the non-antitoxic globulins 
from the serum by the Gibson method eliminates much of the delete- 
rious matter from the serum, so that severe rashes, joint complications, 
fever, and other constitutional disturbances are less likely to occur 
from the antitoxic globulins than from the antitoxic serum from which 
the}^ were obtained. 
We asked ourselves the question whether the precipitated and refined 
serum is less toxic to sensitized guinea pigs than the untreated serum 
from which it was made. Doctor Park kindly furnished us some of 
the precipitated serum and the corresponding untreated serum from 
which it was made in order to carry out these tests. 
« Gibson, R,. B. Journ. biolog. chemistry Vol. 1, Nos. 2 and 3, 1906. 
&Park, William H., and Throne, Binford: The results of the use of “refined diph- 
theria antitoxin,” Gibson’s “globulin preparation,” in the treatment of diphtheria. 
Trans. Assn. Am. Physicians, Vol. 21, 1906, pp. 259-267. 
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