PROTECTIVE INOCULATIONS. 339 



the publication of tlie paper from which the above quotation is made. 

 Under these circumstances the writer feels justified in again calling 

 attention to his priority in the discovery of this important pathogenic 

 niicrococcus, and in objecting to its beiug described as "Frankel's 

 pneumococcus, " the " diplococcus of Frankel," etc. 



In my paper above referred to (July, 1885) I described this micro- 

 coccus under the name of Micrococcus Pasteuri, but in my " Manual 

 of Bacteriology " (1892) it is described under the name of Micrococcus 

 pneumonias crouposce. 



This micrococcus is very pathogenic for mice and for rabbits, less 

 so for guinea-pigs and for dogs. Like other pathogenic microorgan- 

 isms of the same class, it varies greatly in virulence when obtained 

 from different sources. In the saliva of healthy persons, which 

 seems to be its normal habitat, it sometimes has comparatively little 

 virulence. On the other hand, when contained in the blood or in an 

 exudate from a serous cavity of an infected rabbit or mouse, it is very 

 virulent. In one instance (1881) the writer has seen a fatal result in 

 a dog from the subcutaneous injection of one cubic centimetre of bloody 

 serum from the subcutaneous connective tissue of a rabbit recently 

 dead. 



Pneumonia never results from subcutaneous injections into sus- 

 ceptible animals, but injections through the thoracic walls into the 

 lung may induce a typical fibrinous pneumonia. This was first de- 

 monstrate,d 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 portion of the lung, 

 into the lungs of rabbits. Gameleia has also induced pneumonia in 

 a large number of rabbits, and also in dogs and sheep, by injections 

 directly into the pulmonary tissue. Sheep were found to survive sub- 

 cutaneous inoculations, unless very large doses (five cubic centimetres) 

 of a virulent culture were injected. But intrapulinonarj' inoculations 

 are said to have invariably produced a typical fibrinous pneumonia 

 which usually proved fatal. In dogs similar 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." 



Without doubt an attack of pneumonia is followed by a certain 

 degree of immunity of longer or shorter duration. According to 

 Huge, who has made a careful study of the subject, relapses are 

 very infrequent indicating a temporary immunity but subsequent 

 attacks are more likely to occur in those who have once suffered an 



