368 DISEASES OF UNCERTAIN ETIOLOGY 



Bile appears about tlie fifth or sixth day. Red cells may be present, 

 leucocytes are rare. Casts, h\a!ine, i^ranular and epithelial appear in 

 turn. 



I'rea is diminished in bad cases. 



The diazo reaction is usually absent. 



The Yomit. P^irst white, consisting of mucus; acid and colourless, 

 or it may be blood-stained. 



Then red, consisting cliiefly of bright, red blood. 



Later black, consisting of red cells, debris, fat, epithelial cells, 

 micro-organisms and hydrochloric acid in traces. The IICI converts 

 the hb. into acid hcLMiiatin giving the black cohjur. 



The Immunity. 



Racial immunity, so-called, in endemic regions is really due to 

 their having had mild attacks in childhood. 



Acquired immunity usually is lifelong, and is given by a typical 

 attack. 



Relative immunity is acquired by receiving an inoculation of 

 infected blood serum, heated for five minutes to 55°C. 



It has been shown conclusivelv that negroes of the West Coast are 

 not immune to yellow fever but are as liable as whites, 



BUT 

 the practitioners of Guayac|uil recognize the natural immunity of very 

 young children and have presented evidence in support of their views 

 (O'Brien). This appears to pass off with age, during which transient 

 periodic mild attacks give an acquired immunity. 



P. M. 



The skin is yellow and stained with hccmorrhages. 



The buccal mucosas is fissured, the mouth may contain blood. 



The liver is yellowish brown, h^emorrhagic, cells swollen and fatty. 



The gall-bladder contains inspissated bile, perhaps mixed with 

 blood. 



The spleen is congested and soft, normal in size. 



The gastro-intestinal tract is full of black tarry blood. 



The mesenteric glands are sometimes enlarged. 



The kidneys are congested, not enlarged. 



The urinary tubules show fatty degeneration with granular debris 

 in the urine. 



The urinary bladder is usuallv empty. 



The pericardium may show effusions and the heart ecchymoses. 



The pleurae may show haemorrhages; the lungs are often congested. 



The uterine mucosa? are congested and the organ mav contain 

 blood. 



The meninges are congested and may show hcemorrhagic spots 



