PNEUMONIA. 301 



which permits of their being seen without careful in- 

 spection. 



In bouillon the organisms grow well, clouding the 

 medium very slightly. 



Milk is quite well adapted as a culture-medium, its 

 casein being coagulated. 



No growth can be secured upon potato at any tem- 

 perature or by any manipulation yet known. 



When it is desired to maintain the virulence of a cul- 

 ture, it must be very frequently passed through the body 

 of a rabbit. 



If a small quantity of a pure culture of the virulent 

 organism is introduced into a mouse, rabbit, or guinea- 

 pig, the animal dies in one or two days. Exactly the 

 same result can be obtained by the introduction of a 

 piece of the lung-tissue from croupous pneumonia, by 

 the introduction of some of the rusty sputum, and gener- 

 ally by the introduction of saliva. 



The post-mortem shows that an inflammatory change 

 has taken place at the point of inoculation, with a fibrin- 

 ous exudate resembling somewhat that in diphtheria. 

 At times, and especially in dogs, there may be a little 

 pus formed. The other appearances are those of a 

 general disturbance. The spleen is much enlarged, is 

 firm and red brown. The blood in all the organs contains 

 large numbers of the bacteria, most of which exhibit a 

 distinct lanceolate form and have their capsules very 

 distinct. The disease is a pure septicemia unassociated 

 with pronounced tissue-changes. 



In cases of the kind described the lungs show no pneu- 

 monic changes. Likewise, if the hypodermic needle 

 used for injection be plunged through the breast-wall 

 into the pulmonary tissue, no pneumonia results. Mon- 

 ti, however, claims to have found that a true character- 

 istic pneumonia results from the injection of cultures 

 into the trachea of susceptible animals. This observa- 

 tion lacks confirmation. 



Not all animals are susceptible. Guinea-pigs, mice, 



