AGGRESSINS 287 



These directions are not very definite, but clinical experi- 

 ence to date justifies them. It is worth the time and money 

 to one who wishes to use vaccines to learn from one who 

 has had experience both in making and administering them, 

 and then to remember that each patient is an individual 

 case for the use of vaccines as well as for any other kind of 

 treatment. 



AGGRESSINS. 



Opsonins have been shown to be specific substances which 

 act on bacteria in such a way as to render them more readily 

 taken up by the leukocytes. By analogy one might expect 

 to find bacteria secreting specific substances which would 

 tend to counteract the destructive action of the phagocytes 

 and bactericidal substances. Bail and his co-workers claim 

 to have demonstrated such substances in exudates in certain 

 diseases and have given the distinctive name ''aggressins" 

 to them. By injecting an animal with " aggressins," anti- 

 aggressins are produced which counteract their eft'ects and 

 thus enable the bacteria to be destroyed. The existence 

 of such specific bodies is not generally accepted as proved. 

 The prevailing idea is that bacteria protect themselves in 

 any given case by the various toxic substances that they 

 produce, and that ''aggressins" as a special class of sub- 

 stances are not formed. 



