LOCKE AND HIRSCH 1055 



of the whole serum after diminution or augmentation of the electrolyte content, as 

 used by the very early investigators of the isolation problem, have recently been re- 

 vived for the examination of hemolysin and of antipneumococcus immune sera." 

 These methods are of considerable practical value for the economical concentration 

 of immune sera intended for therapeutic use, but have not as yet in any way ap- 

 proached the purification obtained by the specific adsorption method. 



The demonstration of the isolation and nature of the immune substances awaits 

 the establishment of more perfect criteria of purity rather than the elaboration of 

 more perfect methods of separation. The problem has a considerable practical im- 

 portance in view of the strong possibility that immune substances can be prepared 

 more economically and with greater therapeutic effectiveness by a synthetic com- 

 pounding of antigen and pre-antibody substance, in vitro, once the nature and origin 

 of the latter material is established. 



'Locke, A., and Hirsch, E. F.: op. cit., 35. SiQ- 1924; Coulter, C. B.: /.General Physiol., 10, 

 545. 1927; Felton, L. D.: /. Infect. Dis., 37, 199, 309. 1925. 



