148 Perspecfives in Microbiology 



liquors of beef lung, to beg some of the material and test it 

 with Type XIV antipneumococcus serum. Nearly one 

 third of the antibody was precipitated. The Ohio workers 

 had shown that galactose was present in the lung galactan 

 in three glycosidically linked forms: otherwise unsubsti- 

 tuted, singly substituted, and doubly substituted. The un- 

 substituted end groups are glycosidically linked to the 3 

 or 6 positions of other galactose radicals, and all linkages 

 are 1,3, or 1,6, or 1,3,6. This does not help much, since 

 there are also three galactoses in the repeating unit of the 

 Type XIV polysaccharide, and their linkages are unknown. 

 A clue, however, was furnished by tamarind seed polysac- 

 charide, a commercial thickener of jellies, from India. This 

 carbohydrate consists of a main chain of xylose and glucose 

 units, two thirds of the latter branched at the 1,4,6 posi- 

 tions, making the substance reactive with Type II anti- 

 serum. Attached glycosidically to the main chain are single, 

 otherwise unsubstituted galactose units, and these suffice 

 to precipitate a portion of the antibodies in Type XIV 

 antiserum. Moreover, such galactose end groups are the 

 only structures in common with the lung galactan, and 

 since both polysaccharides precipitate Type XIV anti- 

 serum, it may be predicted with confidence that not only 

 will all carbohydrates containing unsubstituted galactose 

 units precipitate this antiserum, but that one, at least, of 

 the three galactose radicals in the Type XIV polysac- 

 charide will also be found to occur as an unsubstituted end 

 group. The former prediction has been verified with 

 karaya gum and gum arabic, and it is hoped to test the lat- 

 ter prediction chemically in the near future. Here again, 

 then, part of the problem has been solved, but much re- 

 mains to be done. 



