824 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



usually develops, dry at first and later productive as pneumonia sets 

 in. Herpes sometimes occurs. The prostration and depression of 

 influenza are a characteristic feature. After three to five days in the 

 milder types, the temperature comes to normal by lysis, but convales- 

 cence as a rule is slow. Cases developing pneumonia are usually 

 marked by cyanosis, a secondary rise in temperature, a change in the 

 sputum from a scanty mucoid to a purulent and often blood-stained 

 character, an increase in the respiratory rate, and the appearance of 

 varying physical signs in the chest. 



The most noticeable pathological findings in fatal cases occur in 

 the chest. Generally speaking, there is a very moist, confluent, lobular 

 pneumonia showing haemorrhagic zones together with firmer yellow- 

 ish areas large or small, sometimes lobar in extent and occasionally 

 showing fibrin. The cut bronchioles yield a thick yellowish pus and 

 often appear as centers of greater or less necrosis. This lesion suggests 

 that of the purulent bronchitis described by English writers in 1916 

 and 1917 but of more advanced character and with an added pneu- 

 monia. A tracheo-bronchitis is present which is usually haemorrhagic. 

 Haemorrhage in the abdominal recti is found in some of the severe 

 cases. 



There is no doubt that the specific organism enters and leaves the 

 body by the mouth and nose. 



It seems probable that an immunity following the disease may 

 endure for at least a few months, but it is difficult to secure data for 

 longer periods. 



No specific substances are known for the treatment and prevention 

 of the disease except that prophylactic vaccination against the second- 

 ary organisms such as B. influenza, the pneumococcus and streptococ- 

 cus, etc., have been tried with reported success both in England and 

 America. The mask has probably been an aid against the spread. 



Bact. influenza 



This organism was described by Pfeiffer in 1892 as occurring in large numbers 

 in the purulent bronchial secretion expectorated by influenza patients, and until 

 the present pandemic was regarded by many as the established cause of the disease. 

 In pure cultures the bacterium is 0.2^1 wide by o.5/x long with occasional threads up 

 to 2/j. in length. Larger forms are seen on boiled blood agar. The arrangement is 

 usually single, occasionally in pairs end to end arid rarely in chains. The bacterium 

 is non-motile and does not show spores or capsules. It does not stain very readily, 



