28 IMMUNE SERA 



previously shown that the proteids thrown out of 

 solution by acetic and carbonic acids contained 

 none of the antitoxin. In 1901 Atkinson * showed 

 that the globulins increase markedly in the serum 

 of horses as the antitoxic strength increases. The 

 most recent work on this subject is that of Gibson, 2 

 who shows that if the ammonium sulphate precipi- 

 tate (globulins, nucleo-proteids, etc.) is treated with 

 saturated sodium chloride solution, practically all 

 the antitoxic fraction passes into solution. Gibson's 

 was the first really practicable method of concentrat- 

 ing the antitoxin. By means of it solutions of 

 antitoxic globulin could easily be made to contain 

 1500 units per cc. Continuing Gibson's work, 

 Banzhaf discovered that if the antitoxic serum or 

 plasma was heated to 57 for 18 hours, there was 

 a change of a considerable portion of the soluble 

 globulins (soluble in Nad solution) into insoluble 

 globulins. The antitoxin remained unchanged. 

 This procedure, therefore, permits of a still greater 

 elimination of the non-antitoxic proteids. 



Gibson has recently studied the possibility of 

 differentiating other antibodies by means of their 

 precipitation characteristics. He believes that a 

 differentiation of the antibodies into those precip- 

 itated with the pseudo globulins and with the 

 euglobulin fractions, according to the Hofmeister 



1 Atkinson, Jour. Exper. Medicine, Vol. i, 1901. 

 1 Gibson, Journ. Biological Chemistry, Vol. i, 1906. 



