26 



this implies that the standard test should be in accordance with 

 the orthodox agglutination test. The question of the isolation 

 of the pneumococcus, whether direct from the sputum or through 

 the mouse, is debatable. For my own part I think it is preferable, 

 wherever experiments on animals can be performed, to inoculate 

 the sputum intraperitoneally into a mouse and to recover the 

 pneumococcus from the heart's blood. It is a simpler method 

 and yields more positive results than direct plating. The 

 peritoneal washings provide a ready and certain means of 

 diagnosing the type. It has been shown that more than one 

 type of pneumococcus may occur at the same time in a sputum ; 

 the predominant virulent type, which will multiply in the mouse, 

 is most likely to be the cause of the disease in the human being. 

 With regard to certain technical details in the agglutination test, 

 my own experience indicates that (1) the suspensions should be 

 whole broth cultures, since they give the sharpest results; 

 (2) agglutinating sera should be prepared in the rabbit, since this 

 animal yields the most specific sera; (3) strains used for im- 

 munisation should be maintained in virulence and should therefore 

 not be subcultivated for long periods on solid media. 



Distribution of Types in the Present 

 Series of 150 Cases. 



The following figures give the percentage occurrence of the 

 American types of pneumococci in the 150 cases of lobar 

 pneumonia. In order to ascertain whether these figures are 

 a sufficiently large sample to represent the normal incidence 

 of the various types hi the period, area, and circumstances of the 

 inquiry, the results are analysed to show the relative proportions 

 in each set of 50. For the purpose of comparison with the 

 original American figures, those strains which did not react with 

 any serum of the three " fixed " types are classed provisionally 

 as " Type IV." The question of the American atypical Type II 

 strains which I have included in the " Type IV " group will be 

 referred to later. 



It will be seen that the above results are in fairly close agree- 

 ment with the American results. They found* in 454 cases 



* Monograph of the Rockefeller Institute for Medical Research, 16th 

 October, 1917. 



