MICROCOCCI 225 



The sputum of cases of acute lobar pneumonia, injected 

 into mice or rabbits, produced more constantly a septi- 

 caemia with fatal results than did the sputum of healthy 

 individuals. In this " sputum septicaemia," lance-shaped 

 cocci in pairs were most frequently found. Weichselbaum 

 in 1886 examined 129 cases of all forms of pneumonia, 

 and described four organisms which he found, the most 

 frequently present being the one now known as the pneumo- 

 coccus. It was present in all forms. The Streptococcus 

 pneumoniae (now believed to have been a more vigorous 

 pneumococcus) was next in frequency, then the pneumo- 

 bacillus, and lastly the Staphylococcus pyogenes aureus. 



Description. A small coccus, generally occurring in pairs, 

 and surrounded by a definite capsule. The cocci are lance- 

 shaped, like the flame of a candle; and in the pair have 

 the pointed ends opposed. A close resemblance to a 

 bacillus is thus formed. The capsule is characteristic in 

 preparations from the sputum and tissues, but is only got 

 in serum cultures, and is absent at times even in the 

 sputum and in scrapings from the lung. The coccus is 

 non-motile, non-flagellar, non-sporing. It is readily 

 stained by the usual aqueous aniline dyes, and it is Gram- 

 positive. The capsule is well shown in specimens stained 

 by Gram and counter-stained : it takes the latter. 



Cultures. Growth on the ordinary media is variable. 

 From sputum it is best isolated by animal injection and 

 cultures from the heart's blood. The best temperature is 

 37-5 C. Growth does not take place as a rule below 25 C. 

 The colonies are like drops of dew. Blood serum and blood 

 agar are the best media. In gelatin stab (when growth 

 takes place), a row of minute dots appears, but no lique- 

 faction. In broth, a slight turbidity results, which settles 

 to the bottom of the tube as a dust-like deposit. Cultures 

 rapidly die out, and virulence is quickly lost. In milk, 

 growth is rapid, with acid and clot, and capsules are 

 usually formed. Prolonged life is said to have been got in 

 cultures on ascitic agar and blood-smeared agar. The 

 pneumococcus ferments saccharose, lactose, ramnose, and 

 inulin. 



Habitat. The mucous membranes of the mouth, nose, 

 throat, and conjunctiva. 



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