274 SPECIFIC MICRO-ORGANISMS 



collection of leukocytes and serum, and the streptococci are also 

 found here, especially at the periphery of the reddened area. 

 In follicular tonsillitis and many cases of pseudo-membranous 

 angina as well as in the pharyngitis of scarlet fever, streptococci 

 occur in large numbers, and doubtless bear a causal relation to 

 at least a part of the pathological process. In true diphtheria, 

 streptococci seem to play rather frequently the role of important 

 secondary invaders. From the pharynx the streptococcus 

 may gain access to the middle ear and the mastoid cells, to the 

 meninges, to the trachea, bronchi and lungs, setting up purulent 

 inflammations in any of these locations. It is an important 

 secondary invader in pulmonary tuberculosis. The streptococcus 

 seems also to cause enteritis, particularly in infants. In the puer- 

 perium, streptococci are practically always present in the lochia. 

 In spite of m,any attempts to differentiate between virulent 

 and non-virulent types in this situation, it is still impossible to 

 distinguish them. Probably local conditions in the uterus as 

 well as the general condition of the patient have much to do in 

 determining her resistance to infection of the uterine wall with 

 these normal streptococci. Undoubtedly the frightful epidemics 

 of puerperal fever in some hospitals previous to 1875 were due to 

 the transference of virulent organisms from patient to patient 

 by the attending physicians and nurses. This was first suggested 

 by Holmes (1843) ^nd more definitely proven by Semmelweiss 

 (1861), but their ideas received little credence until the last quar- 

 ter of the nineteenth century. Streptococcus bacteremia is 

 commonly a terminal phenomenon, but it may occur without 

 im.mediate fatal issue, and may result in endocarditis and strepto- 

 coccus arthritis. 



Immunity to streptococcus infection is slight in degree and 

 very temporary. Koch showed that erysipelas could be repeat- 

 edly produced on the same area of the skin by inoculation at inter- 

 vals of 10 to 12 days. Rabbits and horses acquire a high degree 

 of immunity when treated with gradually increasing doses of 

 many different strains of streptococci. The serum of such 



