552 BIOLOGY OF PNEUMOCOCCUS 



opalescence — the initial point — it was possible to calculate the 

 total amount of water necessary to obtain maximal precipitation. 

 One of the requirements of the procedure was the maintenance of 

 low temperatures with the materials used. Banzhaf and Klein 72 em- 

 ployed a somewhat similar process except that adjustments in 

 hydrogen ion concentration were made, but the authors stated that 

 Goodner's method probably yielded a purer form of antibody de- 

 spite the presence of chill-producing agents. 



There is some evidence that the percentage recovery of Type II 

 antibody is appreciably lower than that of Type I. It has been 

 suggested that the disparity might be due to a difference in the iso- 

 electric points, or zones, of the two types of antibody, and that 

 Type II immune substances might precipitate more completely at 

 a lower hydrogen ion concentration without affecting the yield of 

 Type I immune substances. The question of the solubility of one 

 antibody fraction in the other has also been raised by Savino, 

 Negrete, and Acuna. Observations by Hager, Barnes, and Wight* 

 (1935), are pertinent to the subject. From a single, pooled lot of 

 antipneumococcic serum of Types I and II, four different batches 

 were concentrated by the alcohol method and the antibody precipi- 

 tated at pH 5.0, 6.0, 7.0, and 8.0, respectively. Repeated mouse 

 tests gave the following approximate percentage yield of protective 

 substances: At pH 5.0, Type I, 83 per cent and Type II, 66 per 

 cent ; at pH 6.0, Type I, 80 per cent and Type II, 59 per cent ; at 

 pH 7.0, Type I, 98 per cent and Type II, 93 per cent ; at pH 8.0, 

 Type I, 98 per cent and Type II, 85 per cent. No acid fraction 

 was removed from the solutions. The results suggest that, under 

 the experimental conditions employed, antibodies of both Types I 

 and II are precipitated more completely at pH values of 7.0 and 

 8.0 than at 5.0 and 6.0, with the optimum at neutrality or there- 

 abouts. The results are also in essential agreement with the earlier 

 observations made by Felton, and by Felton and Bailey, regarding 

 the isoelectric points of antipneumococcal antibodies. It is possible 



* 1935, unpublished. 



