1160 



PHYSIOLOGY 



the red blood- corpuscles. We may regard the amboceptor therefore 

 as having two haptophore groups, one of which anchors on to the red 

 blood-corpuscle, while the other attaches itself to the complement (Fig* 

 485, 7). The amboceptor plus the complement thus comes to resemble 

 the toxin molecule, having a free haptophore group at one end and a 

 toxophore group (the complement) at the other end. The reaction 

 to the injection of the red blood-corpuscles consists in the formation 

 of the amboceptor, which is essentially the anti-body of the red blood- 

 corpuscle (Fig. 485, 8). Similar specific anti-bodies effecting the 

 dissolution of cells or organisms maybe produced by the injection of 

 various species of bacterium or of animal cells, such as leucocytes, sper- 

 matozoa, liver-cells, &c., and there can be no doubt that bacteriolytic 

 substances play a considerable part in acquired immunity. 



FIG. 485. Diagram to show the relation of amboceptor and complement 

 to the animal cell (7) and to red corpuscles (8). (EHRLICH.) 



OPSONINS. In some cases the anti-bodies produced by the 

 injection of living or dead micro-organisms do not bring about actual 

 destruction of the bacteria, but alter them in such a way as to make 

 them more susceptible to the action of the phagocytes. If washed 

 white blood- corpuscles be mixed with micrococci, such as those found 

 in an ordinary boil, they are found to take up the micro-organisms in 

 considerable numbers. The numbers taken up are much increased in 

 the presence of serum derived from an individual who has received 

 repeated minute injections of the dead micrococci in question. To the 

 substance in the serum which thus prepares the micrococci for ingestion 

 by the phagocytes Wright has given the name of opsonins. The 

 opsonic index of the leucocytes of any individual in reference to 

 a given species of microbe is determined by observing the number of 

 the microbes taken up by the leucocytes after treatment with the 

 serum of the individual and comparing it with the number taken 



