CHEMICAL CONSTITUENTS 275 



the horse. The Type VIII polysaccharide also induced fatal 

 anaphylactic shock in guinea pigs passively sensitized with the ho- 

 mologous antiserum from the rabbit but not with a similar serum 

 obtained from the horse. 



Among the many methods applied to the purification of pneumo- 

 coccal carbohydrate, ultrafiltration was employed by Brown. 158 

 By passing broth cultures of Type VIII Pneumococcus through a 

 Sharpies centrifuge and then filtering the clarified effluent through 

 parlodion filters, or by passing broth cultures through a single 

 nitrocellulose-coated alumina thimble, the author effected the 

 elimination of inert material with a consequent enhancement of 

 serological activity. 



ISOLATION OF AN UNIDENTIFIED CONSTITUENT OF THE PNEUMO- 

 COCCAL, CELL 



In the interval elapsing between the first and third papers of 

 Wadsworth and Brown, Felton 413 reported the isolation of what he 

 claimed to be yet another constituent of the pneumococcal cell. 

 This derivative was described as a non-carbohydrate and probably 

 a non-protein substance, possessing the ability to immunize mice 

 against pneumococcal infection. Supplementing his preliminary 

 announcement, Felton 417 in October, 1934, published information 

 which, to a considerable extent, clarified the doubt concerning the 

 true nature of his antigenic "non-poly saccharide and probably 

 non-protein derivative" of Pneumococcus. In the earlier paper, 

 Felton reported that this crystalline substance gave a negative 

 biuret test, a negative Molisch reaction, and also failed to cause 

 precipitation in antipneumococcic horse serum. Further study, 

 however, showed "that the crystalline material lacked immunizing 

 properties, and that in all likelihood the crystals were leucine. In 

 addition, although the substance gave negative Molisch reaction, it 

 was found that the difference in the reduction of copper before and 

 after hydrolysis corresponded to from 0.25 to 0.5 per cent glu- 



