CHAPTEE XVII. 



PNEUMONIA. — INFECTIOUS PLEURO-PNEUMONIA OF CATTLE. — 

 INFLUENZA. 



Acute Croupous Pneumonia. 



Pneumonia is an acute inflammation^ of the lungs with fibrinous 

 infiltration of the air vesicles and interstitial tissue. There are 

 varieties of pneumonia, and one form is commonly believed to be 

 infectious. 



The lung passes through three stages — engorgement, red hepati- 

 sation, and grey hepatisation. In the first stage the lung is of 

 a deep red colour, but still vesicular ; in the second stage the 

 affected part is more or less solid, and has the consistency of liver, 

 owing to the fibrinous lymph which is poured out into the alveolar 

 cavities. In the grey hepatisation, the exudation contains more 

 leucocytes .and less fibrin, and this is followed by the stage of 

 siippurative softening and final absorption. The sputum at the 

 commencement of the disease is rusty, from the presence of blood, 

 and later on has the appearance of prune juice. Examination of 

 the sputum by Gram's method will reveal numerous micro-organisms, 

 and two of these are deserving of special study — the pneumococcus 

 of Priedlander, which is present in a considerable proportion of 

 cases, and Sternberg's micrococcus, which was found in 'sputum by 

 Talamon. 



In 1888, there was considerable prevalence of pneumonia in 

 Middlesbrough, with strong tendency to occur in groups of cases; 

 but there was admittedly room for doubt whether the clinical 

 and post-mortem appearances were not identical with ordinary 

 pneumonia. Dr. Ballard maintained that there were facts and 

 considerations which appeared to show that the disease was com- 

 municable from the sick to the healthy, and that it was a specific 

 febrile disease, and Klein isolated and described the micrococcus 

 present in these cases. 



Bacterium Pneumoniae Crouposse (Pneumococcus, Fried- 



233 



