408 BACTERIA IN CROUPOUS PNEUMONIA. 



single experiment, however, the writer has seen a fatal result in a 

 dog from the injection of one cubic centimetre of bloody serum from 

 the subcutaneous connective tissue of a rabbit recently dead. This 

 shows the intense virulence of the micrococcus when cultivated in 

 the body of this animal. Pneumonia never results from subcutane- 

 ous injections into susceptible animals, but injections made through 

 the thoracic walls into the substance of the lung may induce a typi- 

 cal fibrinous pneumonia. This was first demonstrated by Talamon 

 (1883), who injected the fibrinous exudate of croupous pneumonia, 

 obtained after death, or drawn during life by means of a Pravaz 

 syringe from the hepatized portions of the lung, into the lungs of 

 rabbits. According to See, eight out of twenty animals experi- 

 mented upon exhibited "a veritable lobar, fibrinous pneumonia, 

 with pleurisy and pericarditis of the same nature." Gameleia has 

 also induced pneumonia in a large number of rabbits, and also in the 

 dog and the sheep, by injections directly into the pulmonary tissue. 

 Sheep were found to survive subcutaneous inoculations, unless very 

 large doses (five cubic centimetres) of the most potent virus were in- 

 jected. But intrapulmonary inoculations invariably induced a typi- 

 cal fibrinous pneumonia which usually proved fatal. In dogs simi- 

 lar injections gave rise to a " frank, fibrinous pneumonia which 

 rarely proved fatal, recovery usually occurring in from ten to fifteen 

 days, after the animal had passed through the stages of red and 

 gray hepatization characteristic of this affection in man." 



Monti claims to have produced typical pneumonia in rabbits by 

 injecting cultures of this micrococcus into the trachea. 



From the evidence obtained in these experimental inoculations, 

 and that recorded relating to the presence of this micrococcus in the 

 fibrinous exudate of croupous pneumonia, we are justified in con- 

 cluding that it is the usual cause of this disease, and consequently 

 have described it under the name Micrococcous pneumonias crou- 

 posae. We prefer this to the name commonly employed by German 

 authors " diplococcus pneumonias " because this micrococcus, al- 

 though commonly seen in pairs, forms numerous short chains of 

 three or four elements in cultures in liquid media, and upon the sur- 

 face of nutrient agar may grow out into long chains. It would, 

 therefore, more properly be called a streptococcus than a diplococcus. 



While the micrococcus of pneumonia is not usually seen in the 

 blood in cases of pneumonia it is probably present in small numbers, 

 and secondary infection of the kidneys appears to be a common occur- 

 rence. Thus Frankel and Reiche (1894) report that in twenty-two 

 cases out of twenty-four in which they had an opportunity to exam- 

 ine the kidneys, this micrococcus was present. It was found espe- 



