SIGNIFICANCE OF ALLERGY 551 



out extensive studies on the purification of abortin. Since a sat- 

 isfactory synthetic medium has not been devised, they proceeded 

 to fractionate coll solutions prepared from whole bacteria by 

 acetic acid precipitation. They report tliat the acid-precipitable 

 fraction of abortin is as active as the original solution. The 

 active principle is destroyed within twenty-four hours by tryptic 

 digestion. Schoenliolz and Meyer could ]n-oducc neither specific 

 increased resistance nor allergy by immunizing guinea pigs with 

 killed suspensions of Br. abortus although the agglutinin titer for 

 the antigen wa.s definitely increased. They conclude that allergy 

 results only when active infection is present. Theobald Smith 

 reports that immunization of cattle with a suspension of killed 

 Br. abortus confers only partial and transient immunity. He finds 

 that a vaccine composed of living organisms is superior to the 

 former. For additional information relative to Brucellosis the 

 student is referred to a few supplementary references and to an 

 excellent monograph by Giltner (1934). 



Streptococcus Allergies. — In view of the prevalence and fre- 

 quent chronicity of streptococcus infections it is not surprising 

 that many individuals are allergic to the nucleo-protein fraction 

 of scarlet fever streptococci. Dochez and Stevens (1927) carried 

 out extensive studies on streptococcus allergy in guinea pigs and 

 rabbits. They interpret their results as apparently favoring the 

 theory of Bristol (1926) that the rash and clinical symptoms of 

 scarlet fever may be due to the development of allergy to scarlet 

 fever streptococci or their products. 



Rheumatic Fever. — The etiology of rheumatic fever is not defi- 

 nitely established at the present time. Clawson reports isolating 

 streptococci from a high percentage of blood cultures of rheu- 

 matic fever patients and of producing typical pathological lesions 

 in experimental animals. Herry (1914) and more recently Swift 

 and his colleagues explain the symptoms and clinical course of 

 rheumatic fever upon the basis of streptococcus allergy. An ex- 

 cellent brief summary of this work is given by Zinsser (1931, 

 1939). 



Pneumococcus Infection. — McBroom and Schlesinger report 

 that there occurs an early stage of hypersensitiveness to pneumo- 

 coccus nucleoprotein simultaneously with the early stage of re- 

 sistance. 



