190 BACTERICIDAL OR ANTI-BACTERIAL IMMUNITY. 



The views advanced by Bordet and others of the French school regarding the union 

 of the amboceptors with the cells to be destroyed are less precise than those of Ehrlich. 

 Both, however, recognize the importance of an association of the aniboceptor as a con- 

 dition for the effective action of the complement (cytase). It is for this reason that the 

 amboceptor is called by Bordet, Metschnikoff, and others the sensibilizing substance 

 (substance sensibilisatnct) or the fixative (flxuteur). 



Finally, a long and ingenious series of experiments has led Metschnikoff and his 

 associates to believe that there are two forms of cytase, one called macrocytase, formed 

 by the macrocytes (large lymphocytes derived from the spleen, lymph-nodes, and cer- 

 tain endothelial and connective-tissue cells) and concerned in the destruction of animal 

 cells, such as red blood-cells, leucocytes, spermatozoa, various parenchyma cells, etc. ; 

 and microcyto.se derived from the microcytes (polymorphonuclear leucocytes), which is 

 active in the destruction of bacteria. 



The greatest, diversity of view concerning the cytolytic process between Metschni 

 koff and his followers and the observers of the Ehrlich school relates to the question 

 whether the complement (cytase) does or does not exist free in the blood plasma, for 

 upon the answer to this question depends largely our belief as to the relative signifi- 

 cance of intra- and extracellular cytolysis. This is one of the points concerning which 

 more data are urgently needed.. But even now the views of Metschnikoff are not incon- 

 sistent with the hypothesis of Ehrlich. 



Agglutinative Substances. But there are important adaptive resources 

 of the living body when called upon to deal with foreign material of spe- 

 cial character introduced in unusual ways into its recesses in addition to 

 those just considered. 



The phenomenon of agglutination has been widely known for several 

 years, especially on account of its practical application in diagnosis. 

 The general fact is that as an individual adapts himself that is, be- 

 comes immunized to a special bacterium or its toxic products, either in 

 the course of an infectious disease or as the result of artificial processes, 

 his serum, if placed under suitable conditions in contact with cultures of 

 this special micro-organism, may speedily immobilize the organism if it 

 be motile, and, whether motile or not, lead to its clumping into irregular 

 masses. This reaction has been used, not only as a clinical test of spe- 

 cial infections, ' but also as a means of differentiating species or varie- 

 ties of bacteria. 



But recent studies have emphasized the fact that agglutination is a 

 much more general phenomenon than has been commonly supposed, and 

 is by no means limited to the sera of animals immunized against bacteria 

 and bacterial products. 



For example, in the adaptation of one animal to the red blood-cells 

 of another species, the serum of the adapted animal may become not only 

 lytic but agglutinative also for the corpuscles used for the injections. 

 This is true not only in adaptation to red blood corpuscles but to other 

 cells as well. We have then to add agglutinative substances or aggluti- 

 nins to the list of those which are developed in the body in this form of 

 adaptation. (See Table, page 193.) These also, within the limits already 

 set forth, are specific. 



Just as the specific red blood-cells are capable of fixing the immune 



'For details of application of the agglutination test see Wood's "Chemical and 

 Microscopical Diagnosis," or other works on clinical pathology. 



