AGGBESSIN 263 



considered this to last as long as the opsonic index remained 

 low, and when this latter began to increase the stage of the 

 "positive" or favorable phase was reached. As has been 

 stated the opsonic index is pretty generally regarded as of 

 doubtful value, though the existence of a period of lowered 

 resistance is theoretically probable from the fact that the 

 body cells are called upon suddenly to do an extra amount 

 of work and it takes them some time to adapt themselves. 

 This time, the "negative phase," is much better determined 

 by the clinical symptoms, general and especially local. It 

 is good practice to begin with a dose relatively small. The 

 result of this is an indication of the proper dosage and also 

 prepares the patient for a larger one. The second dose 

 shotild follow the first not sooner than three or four days, 

 and should be five to seven days if the first reaction is 

 severe. These directions are not very definite, but clinical 

 experience 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 indi- 

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

 kind of treatment. 



AGGRESSIN. 



Opsonins have been shown to be specific substances which 

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

 ily 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," antiaggressins are produced which counteract 

 their efl'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 substances are not formed. 



