30 QUATERCENTENARY STUDIES IN PATHOLOGY 



one adds a small quantity of the blood serum of a patient sufifering from 

 acute pneumonia to a small quantity of the corpuscles of a normal 

 individual and examine in hanging-drop, the red blood corpuscles are 

 clustered into large-meshed masses. Dilution with normal saline in 

 sufficient quantity abolishes this reaction. A better result was obtained 

 in the later cases of acute pneumonia, in which I used long sedimentation 

 tubes used for Widal's macroscopic typhoid reaction. The dilutions 

 borne were not very high. Many refuse to become agglutinated in i : 4 

 or I : 10. In the case of empyaema, which had been discharging for two 

 years, the blood serum agglutinated my corpuscles in dilution i in 20, 

 and the fluid from the pus i in 4. The agglutination usually began one 

 or even two days before the crisis, and continued for a week after. The 

 agglutination of the red corpuscles does not seem to stand in close 

 relation to bacterial agglutination, as the latter was very slight, if at all 

 present, in cases where the red cells were very markedly agglutinated. 

 That the property lies in the serum is of easy demonstration, since the 

 haemagglutinin is thermolabile, being destroyed by 60° C. like the 

 opsonin and also the haemolysin. The addition of normal sera to the 

 hsemagglutinating serum is, as a rule, not capable of inhibiting 

 hsemagglutination. 



Bacterial Agglutination. — In 1891, a phenomenon very close to 

 agglutination was observed by Metschnikofl* (36), even before the 

 publication of the papers of Gruber and Durham in 1896. He noted 

 that in the serum of rabbits immunised against the pneumococcus the 

 growth was in long coiling chains, while the same organisms in normal 

 rabbits' serum have the usual diplococcic form. These facts were amply 

 verified and more closely investigated by Mosny, Kruse and Pansini (37), 

 Washbourn, Bezangon and Griffon (^8), and others. 



The agglutination of the pneumococcus in the sense of the Gruber- 

 Widal reaction with the microbes in bouillon culture after addition of 

 quantities of specific serum was first described by Neufield, who comes to 

 the conclusions : — 



1. The occurrence of a strong agglutinating serum in immunised 



rabbits is entirely independent of the degree of immunity. 



2. The agglutination phenomena are specific for the pneumococcus. 



3. The agglutination of the pneumococcus shows many peculiarities, 



among them the great resistance of the bacteria against high 

 degrees of heat. (394) 



