POLYSACCHARIDES OF MICRO-ORGANISMS 357 



The polysaccharide from Type XIV pneumococcus 

 resembles that of Type IV in not containing a uronic 

 acid group. It is constituted of one molecular proportion 

 of acetyl glucosamine and three molecular proportions 

 of galactose. It closely resembles the Blood group A 

 specific polysaccharide which occurs in group A red 

 blood corpuscles and which can be isolated from saliva, 

 gastric mucin, commercial pepsin and peptone. The 

 two substances are nob identical, since the blood group 

 A substance contains nitrogen in addition to that as 

 glucosamine, and the blood group A substance does not 

 give a cross precipitin reaction with antisera to Type XIV 

 pneumococci prepared in rabbits, although strong cross 

 reactions are found when horse antisera are used. Horse 

 antisera to Type XIV pneumococci agglutinate human 

 red cells of all groups. 



Pneumococci resemble Shigella dyseiiterice and Sal- 

 monella schottmuUeri in containing the Forsmann hapten 

 which is capable of provoking lysins for sheep's red 

 blood corpuscles when injected into animals. In the 

 case of the pneumococci it is a lipo -polysaccharide 

 complex (carbohydrate F) associated with the bacterial 

 bodies. It is probably made up of the species specific 

 carbohydrate-C and a lipin fraction, chemically bound 

 to it. The lipin, constituting 6-5 per cent, of the poly- 

 saccharide, is devoid of nitrogen and phosphorus, has 

 m.p. 39-41 °C. and an acid equivalent 372 ; it is possibly 

 a C24 compound. Carbohydrate-C contains no lipin. 



Enzymes have been found in various soil organisms, 

 for example Bhodobacillus palustris and a Myxococcus, 

 which hydrolyse the pneumococcal polysaccharides 

 specifically. Eh. palustris attacks only Type VIII 

 polysaccharide and not those of Types I, II or III. 

 Another soil organism gives an enz^Tne attacking Type III 

 polysaccharide only. 



