THE SOLUBLE SPECIFIC SUBSTANCE OF FRIED- LiiNDER’S BACILLUS

The methods of isolation and the immunological significance of specific carbohydrates from the three fixed types of Pneumococcus and of Friedlander’s bacillus have been described in a series of communications from this laboratory (1). These unusual polysaccharides, which are believed to be identical with the capsular material of the microorganisms from which they are derived, have been isolated as nitrogen-free,’ amorphous compounds possessing marked acidic properties. They are complex carbohydrates built up apparently from molecules of hexose and hexuronic acids in varying proportions. Although no contention has been made that these polysaccharides are pure distinct chemical individuals, a fair amount of evidence has been gathered which supports this view. These carbohydrates have many physical and chemical characteristics in common; they show distinct differences, however, in the degree to which they rotate the plane of polarized light, in their acid equivalent values, and in the selective specificity which they show toward antibacterial serum. The properties of these carbohydrates are briefly given in Table I. The polysaccharide from the Type A Friedlander bacillus resembles the Pneumococcus Type III specific carbohydrate in some of its chemical properties, though immunologically the two compounds are totally unrelated. Both polysaccharides have