502 



IMMUNITY 



fowl with tetanus toxin, as compared with that obtaining in a 

 susceptible animal, but the results have been somewhat contra- 

 dictory. Accordingly, a general statement on this point cannot 

 at present be made, though in all probability variations in the 

 susceptibility to the toxophorous group will be found to play a 

 very important part. It has been shown by Muir and Brown- 

 ing by means of hsemolytic tests that the toxic activity of com- 

 plement, after it has been fixed to the corpuscles, varies very 

 much ; in some instances an amount of complement, which would 

 rapidly produce complete lysis of one kind of corpuscle, may 

 have practically no effect on another, even though it enters into 

 combination. These results are of importance in demonstrating 

 how the corresponding molecules of different animals may vary 

 in sensitiveness to toxic action. 



