245 



is the bacillus which I have obtained most frequently in my cultures from 

 blood and tissues, and which has been present most constantly and 

 abundantly in cultures from material obtained post-mortem from the 

 stomach and intestine and from the alvine discharges of the sick." (Report 

 on the Etiology and Prevention of Yellow Fever, p. 181). 



Now, if it be remembered that in almost all the cases investigated by 

 Dr. Sternberg the stomach or intestine contained black vomit, and belonged 

 therefore to the melano-albuminuric form, the fact that the B. coli com- 

 mune was so frequenty found in the blood and tissues very few hours after 

 death must be considered as a direct confirmation of the secondary in- 

 fection, which I had previously suggested. Subsequent discoveries in 

 Europe have now brought to light the role of the B. coli commune as a 

 frequent source of secondary infections, and also its pathogenic influence 

 upon the liver and kidneys. The fatal influence of such a complication 

 upon a patient already reduced by the primary yellow fever infection may 

 therefore be readily assumed. Other bacilli have, however, been obtained 

 by Dr. Sternberg and others from the tissues of yellow fever subjects; it 

 is possible, therefore, that in certain cases the secondary infection may 

 proceed from other gastro-intestinal microbes besides the B. coli commune. 



Pathogenesis. — While acknowledging that several missing links would 

 have to be supplied before a scientific explanation could be given of the 

 phenomena of yellow fever, some plausible deductions may be formed in 

 view of the facts set forth in the clinical history, morbid anatomy, and 

 bacteriology of the disease. 



The most prominent features in the "non-albuminuric" and the 

 "plain albuminuric" forms point: (a) to some pathological process going 

 on in the walls of the small vessels and capillaries (by which these are 

 rendered more permeable and brittle) as the cause of certain 

 important symptoms; (b), to a stimulation of the vasodilator centers as 

 the raison d'etre of the congestion observed during the period of invasion 

 and also of the subsequent relaxed condition of the blood vessels when the 

 mass of blood has been, reduced in consequence of filtration of the blood 

 serum through the altered walls of the capillaries. The filtration of the 

 blood serum and the diminished resistance of the vascular endothelium 

 would account for the concentration of the blood, for the yellow colour of 

 the tissues, for the presence of albumen in the urine (even when no 

 actual nephritis has developed), and for the haemorrhagic tendency. 



A haemorrhagic tendency, constituted by a weakened condition of the 

 walls of capillaries, would requiere the intervention of some other factor 

 before passive haemorrhages could be produced, — a factor capable of 

 bringing about a local hyperaemia that should put the capillary walls on 

 the stretch. The menstrual molimen in women, a fit of coughing or 

 sneezing, a muscular effort, might in particular cases account for the 

 bleeding from the uterus or nose, and for effusion of blood under the 



