M KTHODS OF EXAMINATION 241 



qualities of the blood of pneumonic patients, especially with a 

 view to throwing light on the nature of the febrile crisis. 

 According to some results, the opsonic index as compared with 

 that of a healthy person is not above normal, but if the possible 

 phagocytic capacities of the whole blood of the sick person be 

 taken into account, these will probably be much above normal 

 in consequence of the leucocytosis which usually accompanies a 

 successful resistance to this infection. It has been observed, 

 however, that as the crisis approaches in a case which is to 

 recover the opsonic index rises, and after defervescence gradually 

 falls to normal. As bearing on the factors involved in the 

 successful resistance of the organism to the pneumococcus, it 

 has been noted that avirulent pneumococci are more readily 

 up^mised than more virulent strains. It is further stated that 

 avirulent cultures of the pneumococcus can be made to resist 

 phagocytosis if they are treated with the products of the 

 autolysis of virulent strains or with washings from such strains, 

 and that virulent cocci if washed with saline become capable of 

 1 is -ing readily phagocyted. Further observations along such 

 lines are to be looked for with interest, and it may be said that 

 Wright's vaccination methods have been applied to the treatment 

 of pneumonic cases, and in certain instances are said to have 

 been followed by favourable result. It may be noted here, in 

 conclusion, that in man it is probable that immunity against 

 pneumonia may be short-lived, as in a good many cases of 

 pneumonia a history of a previous attack is elicited. 



Agglutination of the Pneumococcus. If a small amount of a 

 culture of Fraenkel's pneumococcus be placed in an anti-pneumo- 

 coccic serum, an aggregation of the bacteria into clumps occurs. 

 Such an agglutination, as it is called, is frequently observed 

 under similar circumstances with other bacteria. The pheno- 

 menon is not invariably associated with the presence of protective 

 bodies in a serum, but it has been used for diagnostic purposes 

 in the differentiation of sore throats due to pueumococcus infec- 

 tion from those due to other bacteria. Whether the method is 

 reliable has still to be proved. It has been shown that a serum 

 which agglutinates the pneumococcus may also agglutinate 

 streptococci isolated from various sources. Such organisms are, 

 however, not so uniformly agglutinated by a pneumococcus 

 serum as are pneumococci isolated from pneumonic cases. 



Methods of Examination. These have been already 



described, but may be summarised thus : (1) Microscopic. 



Stain films from the densest part of the sputum or from the 



area of spreading inflammation in the lung by Grain's method 



16 



