MECHANISM OF ANTIGEN-ANTIBODY REACTIONS 211 



Ehrlich's View. — This two-phase hypothesis of Bordet was 

 vigorously opposed by Ehrlieh* who conceived of agglutinin as 

 having chemical groups that caused clumping. Referring to Bor- 

 det 's work he says, "The attempt has been made to interpret the 

 immunity reactions from the standpoint of colloid chemistry. . . . 

 I see absolutely no advantage in such a method, and I have grave 

 fears that it will result in checking further progress along this 

 line. Structural chemistry, on the otlier hand, has not only served 

 to explain all the phenomena in imuuniity studies but has also 

 proved a valuable guide in indicating the lines along which further 

 progress might be made. ' ' 



This difference of opinion between those holding to the physico- 

 chemical theories and those equally ardent advocates of theories 

 based upon structural chemistry led to an interusive study of anti- 

 gens and the factors governing specificity and to the mechanism 

 of the immunological reactions. The phenomenon of specificity has 

 been discussed at lengtli in Chapters XVIF, XVIII, and XIX. 



Subsequent Lines of Research. — In the studies of the meciiani.sm 

 of clumping or agglutination of l)actoria by immune sennn, three 

 interesting lines of investigation have contributed to our present 

 concepts. These may be enumerated as follows : 



1. Studies to determine whether the law of multiple propor- 

 tions holds when bacteria combine with agglutinin. 



2. Studies of the effect of varying salt concentrations on mem- 

 brane potential and cohesive forces of unsensitized and sensitized 

 particulate matter that has previously been made to adsorb a 

 specific protein and bacteria before and after the adsorption of ag- 

 glutinin. 



3. Studies relative to the nature of cellular surfaces and molecu- 

 lar orientation before and after the adsorption of specific agglu- 

 tinins. This work has been done largely by I\Iudd and IMudd 

 (1924, 1926, 1927) using their ' ' interfacial tension technic." 



Studies on Effect of Dilution on Adsorption. — In 1902, 

 Eisenberg and Volk found that if a constant amount of bacteria 

 were mixed with equal amounts of varying dilutioiLs of immune 

 serum, the bacteria removed a greater percentage of the agglutinin 

 content from the higher dilutions. In the lower dilutions where 



•Reprinted by permis.sion from Studiffi in Immunitij by Ehrlich-Bolduan, 

 published by John Wiley & Sons, Inc. 



