1919] VETERINARY MEDIGINfc. 575 



or to phosphate peptone agar, which was then inoculated with small amounts of 

 culture suspensions. The tubes were incubated at 37° C. and observations 

 made daily for several days. 



" The growth of all pathogenic bacteria studied was favorably influenced 

 by the addition of small amounts of tissue extracts. Beef heart, rabbit and 

 cat tissues, and human nasal secretions contain substances favorable to the 

 growth of the organisms tested. The mucosa of different organs, spleen, liver, 

 and kidney, are relatively rich in these substances, while muscle is relatively 

 poor. The favorable effect of the extracts is manifested by an enhancement 

 of growth and a reduction of lag." 



Evidence is furnished indicating that the favorable effect upon bacterial 

 development is produced by the water-soluble vitanuns present in the tissue 

 employed. 



Studies on the biology of streptococcus. — I, Antigenic relationships be- 

 tween strains of Streptococcus heniolyticus, A. R. Dochez, O. T. Avery, and 

 R. C. Lancefield (Jour. Expt. Med., 30 (1919), No. 3, pp. 179-213).— Th<^ prob- 

 lem of the complete biological classitication of pathogenic organisms is con- 

 sidered by the authors to consist of (1) the development of reliable methods 

 for the determination of antigenic dilferences betv\'een members of the species 

 and the application of these methods to the discovery of the immunological 

 relationships between a limited number of strains, (2) the application of this 

 tentative classification to a large number of strains of the organism obtained 

 under normal conditions of pathogenicity, and (3) a comparison by the same 

 methods of the pathogenic with the saprophytic varieties of the organism. 



This paper presents a partial study of /S. hemolyticus in accordance with the 

 plan outlined above. A technique was developed for studying the immunolog- 

 ical reactions of agglutination and protection in 12.5 human strains of hemo- 

 lytic streptococci obtained from various sources. By the reaction of aggluti- 

 nation four distinct immunological types, two types at present not completely 

 investigated, and a certain number of unclassifiable strains were descovered. 

 It was found possible to raise the animal virulence of a certain number of 

 strains to a high degree and to produce antistreptococcic sera of sufficiently 

 high titer for reliable protection tests. In all instances in which this was done 

 tlie protection reaction has corroborated the evidence obtained from the aggluti- 

 nation test. 



These results indicate that 8. hemolyticus of human origin is not a unit 

 type, as was previously supposed, but probably consists of a number of types, 

 at least four of which have been definitely identified. No evidence was ob- 

 tained to support the contention that freshly isolated human strains change 

 their antigenic properties on animal passage, and that this procedure for the 

 development of animal virulence gives a common antigenic character to all 

 strains. On the contrary, the antigenic differences between strains of S. 

 hejiiloyticus which had been passed through animals were as distinct as those 

 between strains which had not been so passed. 



It is emphasized in conclusion that only a beginning has been made in the 

 classification of S. hemolyticus, and that much work must be done before the 

 classification is complete and the relative dominance of the different pathogenic 

 varieties determined. 



The antigenic properties of proteoses, E. B. Fink (Jour. Infect. Diseases, 

 25 (1919), No. 2, pp. 97-123).— This paper consists of a summary of the litera- 

 ture on attempts to demonstrate the forniatjon of antibodies against incom- 

 plete protein molecules, and a report of an investigation of the antigenic prop- 

 erties of proteoses from Witte peptone and from egg white. 



