ORGANISiMS WHICH PRODUCE DISEASE 59 



The Streptococcus rheumaticus is the probable cause of acute 

 rheumatism. Other members of the group are of less im- 

 portance. The Streptococcus pyogenes is a frequent cause 

 of spreading inflammation of serous and mucous membranes, 

 erysipelas, cellulitis, lymphangitis, 1 and the like ; also in 

 localised;suppurations and abscesses usually acute,but some- 

 times chronic, pyaemias and septicaemias are often due to 

 this streptococcus, puerperal fever being a serious septicaemia 

 condition caused by infection of the womb after child-birth, 

 most commonly by the Streptococcus pyogenes, either alone or 

 with other organisms, especially B. coli. The Streptococcus 

 is very frequently found in the throat as a complication of 

 diphtheria and scarlet fever. Either alone or along with the 

 Pneumococcus t it is a common cause of broncho-pneumonia 

 especially after surgical operations on the mouth and neigh- 

 bouring parts, and also in the case of children after measles and 

 whooping-cough. It is a frequent cause of empyema or sup- 

 puration in the pleural cavity around the lung, especially in 

 children. 



Microscopically it is a coccus of about one micromillimetre 

 in diameter, with a tendency to form shorter or longer chains, 

 whence its name, though it is also often found in pairs (see 

 Frontispiece, fig. 4). It is easily stained. On culture, it is 

 much more delicate than the staphylococci, and tends to die 

 out somewhat rapidly. It forms small, rounded, translucent 

 colonies on a solid medium, and it does not liquefy gelatin. 



The Streptococcus rheumaticus in shape and size closely 

 resembles the above, but it is a much hardier and more resis- 

 tent organism. It has been obtained from rheumatic sore 

 throats, and from the various lesions produced by rheumatism 

 in the heart, joints, serous membranes, etc. All the typical 

 lesions of rheumatism have been reproduced by the inoculation 

 of rabbits with this organism even chorea or " St. Vitus' 

 dance," which in its ordinary form is a definitely rheumatic 

 manifestation. Some bacteriologists, however, still deny that 

 this organism is the cause of rheumatism, and speculate as to 

 the possibility of some filter-passing microbe being the causal 

 agent, of which there is at present certainly no proof. 



The Pneumococcus is one of the commonest pathogenic 

 organisms, and may produce, not only acute lobar or crpupous 

 pneumonia, of which it is the specific cause, but also inflam- 

 mations and abscesses in any part of the body. In a more 

 or less non-virulent form it is found in practically every mouth 



1 The inflamed lymphatic channels may show as red lines, for example 

 passing up the skin of the arm when some wound, perhaps on a finger, is 

 infected. 



