CHEMICAL CONSTITUENTS 299 



phorus, and possibly of other elements, some being well supplied 

 with one or the other of these elements, while others would have 

 none. The carbon, hydrogen, and oxygen would be combined to 

 form varying percentages of carboxyl, acetyl, or other radicals, 

 and the presence and proportion of these groups, together with the 

 varying sugars chemically combined, would serve to identify the 

 special serological type to which the pneumococcus belonged. The 

 capsular polysaccharides, furthermore, would differ in their acidic 

 and basic affinities and in their relation to the plane of polarized 

 light. The proportion of these carbohydrates would fluctuate in 

 the different types, and on hydrolysis the substances would yield 

 unequal amounts and various kinds of cleavage products such as 

 glucosamines, sugar acids, and the simpler sugars. With the com- 

 mon protein and the somatic carbohydrate as a nucleus, it would 

 be feasible, as soon as other specific polysaccharides are isolated, 

 to hypothesize a basic reconstruction of all the thirty-two and pos- 

 sibly other as yet undiscovered serological types of pneumococci. 



The capsular polysaccharides would be linked to some of the 

 protein, or even to the lipids, in a combination susceptible to cleav- 

 age by the enzymes of the cell, to the disruptive effects of physical 

 forces, to the lytic action of bile, or to the hydrolyzing action of 

 chemical agents. Their chemical structure is frail, and to the chem- 

 ist they present difficulties in the way of isolating them as they 

 exist in their native state. They call for the utmost care in their 

 separation lest their molecular configuration be distorted or muti- 

 lated. 



While the somatic constituents are sufficient to insure the exist- 

 ence of the cell under ordinary circumstances, the capsular struc- 

 ture composed of type-specific polysaccharides is essential to the 

 complete functioning of the cell as a pathogenic organism, and it is 

 the latter specific complex that gives to a pneumococcus type- 

 specificity and its individual place in the biological and immuno- 

 logical scheme. The capsular material conditions and is associated 

 with the difference between a state of saprophytism and parasit- 



