8 4 



Scientific Proceedings (90). 



of them expectorated specimens, two hundred and forty-nine 

 swabs. Pneumococcus was recovered from seven hundred and 

 ninety-eight specimens, 32.2 per cent. If the unsatisfactory 

 swab group is subtracted, the percentage of positive results for 

 two years is 33.8. In 1916 the annual percentage was 36.4, in 

 1 91 7, 32.5. The lowest percentage at any time was 20, in Novem- 

 ber, 1917; the highest was 49, in March, 1916. During both 

 years the percentage was comparatively high from February 

 through June. Eighty-seven out of the two thousand four 

 hundred and seventy-seven cases studied developed post-operative 

 pneumonia. Pneumococcus was recovered from the pre-operative 

 sputum of forty-seven of these eighty-seven cases, a percentage 

 of 54- 



The table summarizes the findings according to type. 



Incidence. Per Cent. 



Type I S .6 



Type II 10 1.2 



Atypical II 90 11. 2 



Type III 104 13 



Type IV 589 73-8 



Pneumococcus present 798 32.2 



Pneumococcus absent 1.679 



Total cases 2,477 



Some of the Type IV. pneumococci have been classified and all 

 of our twelve groups are represented among them. 2 



A history of contact with a pneumonia case was obtained in 

 only one instance, that of an individual with Type I in the sputum. 

 This was the only member of the Type I group that developed 

 post-operative pneumonia, forming 20 per cent. One with Type 

 II developed post-operative pneumonia, 10 per cent., seven with 

 an Atypical II, 7.7 per cent., nine with Type III, 8.6 per cent., 

 twenty-nine with Type IV, 4.9 per cent. There seems to be no 

 predominance of the virulent types at any one period of the year. 

 Among the Type IV strains, there was great variation in virulence, 

 mice succumbing in from eighteen hours to eight days after 

 inoculation of sputum, the majority within three days. 



Dochez and Avery 3 reported finding the pneumococcus in 

 58.4 per cent, of the mouths of one hundred and thirteen "normal 



2 Olmstead, M. P., Jour. Immunol., 1917, II, 425. 



3 Dochez and Avery, Jour. Exp. Med., 1915, XXII, 105. 



