l62b IMMUNE SERA 



of the accumulated leucocytes. If a bit of the 

 fibrinous exudate is suspended in the exuded 

 serum, it is preserved intact. Nevertheless, by 

 repeated injection of turpentine at short intervals 

 into the pleural cavity, accumulation of leucocytes 

 can be prolonged so that finally a condition is 

 produced in which antienzyme can no longer 

 restrain the enzyme. The softened fibrin of such 

 an exudate quickly disintegrates in the serum of 

 the exudate. These observations, as Opie points 

 out, help to explain how the typhoid bacillus pro- 

 duces abscesses in certain situations such as the 

 kidney and bone; how the pneumococcus, which 

 rarely causes abscess of the lung, in which condi- 

 tions are somewhat similar to those within the pleural 

 cavity, may cause suppuration in other localities, 

 such as the middle ear, or in the subdural space, etc. 

 In addition to the antibodies already mentioned, 

 the animal body produces agglutinins and precip- 

 itins directed against the invading bacteria, but 

 the relation of these antibodies to immunity is not 

 at all clear. So far as the action of the agglutinins 

 is concerned, we have already pointed out (on page 

 36) that this appears to have no destructive effect 

 on the agglutinated organisms. Moreover, while ag- 

 glutination is often observed to precede lysis, there is 

 no reason to believe it a necessary factor in the lytic 

 process, nor even an aid thereto. Whether this list 

 exhausts the number of serum antibodies is doubtful. 



