186 INFECTION AND RESISTANCE 



shaking, there are certain similarities which seem to strengthen the 

 opinion regarding the nature of heat inactivation which we have 

 cited above. For it has been variously shown that prolonged shaking 

 of protein solutions, like heating, gradually leads to coagulation. It 

 would be important to determine whether or not the inactivation by 

 shaking, like that produced by heat, is accompanied by a fall of sur- 

 face tension. 



ALEXIN OR COMPLEMENT FIXATION 



The controversy regarding the multiplicity of alexin and the 

 existence of a "complementophile group" cannot, of course, be re- 

 garded as closed, however much we may lean toward the acceptation 

 of Bordet's point of view, since German experimenters of eminence 

 still adhere to the Ehrlich interpretations. Moreover, it is, of course, 

 extremely difficult to disprove such an assumption as that of the 

 "polyceptor" conception of the complementophile group. However, 

 we may safely assert that the functional unity of complement (and, 

 after all, that is all that Bordet has maintained) is being upheld by 

 the constantly increasing evidence in its favor which is being fur- 

 nished by the practical and experimental application of the phe- 

 nomenon of "alexin fixation" described, in 1901, by Bordet and 

 Gengou. 74 It will be well to bear in mind that this phenomenon 

 should be strictly distinguished from the so-called "complement de- 

 viation" ("Ablenkung"), described by Neisser and Wechsberg. The 

 latter was advanced as an explanation of the inactivity of bacteri- 

 cidal sera when used in too great concentration, as described in an- 

 other place (p. 160) (Neisser and Wechsberg phenomenon), and has 

 been variously utilized as support for the assertion that alexin can 

 unite with unattached sensitizer. It is regarded by most observers, 

 moreover, as untenable in the light of later investigation. In spite of 

 this, the term "Komplement-Ablenkung" has been employed by a 

 number of German writers (see Citron, Vol. 2, "Kraus und Levaditi 

 Handbuch") as synonymous with "fixation" in the sense of Bordet 

 and Gengou. 



The phenomenon of Bordet and Gengou, briefly described, is 

 nothing more than an experimental utilization of the fact which we 

 have discussed at length, that alexin is fixed by antigen and antibody 

 after union, but by neither alone. 



The condition, as observed by them, may be best described by 

 submitting the protocol of the first experiment detailed in their 

 communication : 



An emulsion of a 24-hour slant of plague bacilli was used as 



74 Bordet and Gengou. Ann. de I'Inst. Past., 1901, Vol. 15, p. 289. 



