ANTIGENICITY OF PNEUMOCOCCUS 345 



ings of specific polysaccharide of the first three pneumococcal 

 types and of protein and autolysates derived from organisms of 

 Types I and II was followed by the appearance or increase of the 

 pneumococcidal power of whole defibrinated blood and in most in- 

 stances by the presence of agglutinins and protective antibodies 

 for one or more types of pneumococci. A single intradermal injec- 

 tion of 0.01 milligram of the capsular polysaccharide of pneumo- 

 cocci of Types I, II, or III, or four similar daily injections, re- 

 sulted in the development of antibodies corresponding in type only 

 to that of the antigen injected. A single injection into the skin of 

 autolysates obtained from virulent Type I, II, and III pneumo- 

 cocci gave rise to an increase in the pneumococcidal power of whole 

 blood and the appearance of homologous type-agglutinins and 

 protective antibodies in about one-third of the normal subjects. A 

 similar injection of pneumococcal protein, on the contrary, failed 

 to evoke specific antibodies to any appreciable degree. 



Further evidence of the antigenic action of specific polysaccha- 

 rides injected into the skin of normal individuals was presented by 

 Zozaya and Clark 1590 who, after the intradermal injection of solu- 

 ble specific substance of pneumococci of Types I, II, and III were 

 able to demonstrate homologous precipitins and protective anti- 

 bodies in the serum of human beings, who gave no history of recent 

 pneumococcal infection. Another observation of these authors may 

 be repeated here. It was found that by increasing the surface area 

 of the carbohydrate by adsorption on charcoal or celloidin parti- 

 cles it was possible to evoke antigenic properties in preparations 

 that otherwise appeared to lack immunizing action and to en- 

 hance the action of preparations that already possessed these 

 properties. Francis, 474 in a still more recent paper (1934), de- 

 scribed experiments in which he studied the antigenic action of the 

 original and the acetylated forms of the specific polysaccharide of 

 Pneumococcus. Weekly doses of 0.01 milligram were administered 

 intradermally over a period of three weeks to normal individuals. 

 The experiment showed that both the original soluble specific sub- 



