320 BACTERIA IN CROUPOUS PNEUMONIA. 



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 intrapuhnonary 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 pneumonise crou- 

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

 authors " diplococcus pneumonise" 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. 



G. and F. Klemperer, in 1891, published an important memoir 

 relating to the pathogenic action of this micrococcus. They suc- 

 ceeded in conferring immunity upon susceptible animals by inocu- 

 lating them with filtered cultures of the micrococcus, and in some 

 instances this immunity had a duration of six months. A curi- 

 ous fact developed in their researches was that the potency of 

 the substance contained in the filtered cultures was increased by 

 subjecting these to a temperature of 41 to 42 C. for three or four 

 days, or to a higher temperature (60 C.) for an hour or two. When 

 injected into a vein after being subjected to such a temperature im- 

 111 unity was complete at the end of three or four days ; but the same 

 material not so heated required larger doses and a considerably 

 longer time (fourteen days) to confer immunity upon a susceptible 

 animal. Tlir nmvarinrd material caused a considerable elevation of 

 temperature, lasting for some days. The authors mentioned con- 

 clude from their investigations that the toxic substance present in 

 cultures of Micrococcus pneumonise crouposse is a proteid substance, 

 which they propose to call pneumotoxin. The substance produced 



