240 
TODD AND WOLBACH. 
reduced in number and stain irregularly. The anemia is 
probably due to a blood destruction ; to it is due the pig- 
mentation of all the organs which is so striking in all cases 
of the disease. The enlargement and changes in the lymph 
glands and spleen are probably secondary to the blood 
destruction. 
All those who have worked with Swamp Fever agree in 
looking on blood destruction as the chief feature of the dis- 
ease. The virus which caused the blood destruction and 
the method by which it acts remain unknown. 
Because of their failure to find any pathogenic agent, some observers 
have suggested that the symptoms of Swamp Fever might be produced 
by a toxin, and that the toxin might possibly be absorbed from the 
alimentary tract, where it might be produced by bacteria or by animal 
parasites ; it is well known that auto-intoxication occurs in constipation, 
and that verminous anemia may be produced by Sclerostomes. It has 
also been suggested that Sarcosporidia might account for some of the 
symptoms of Swamp Fever. 
Neither of these suggestions is tenable, for the virus which causes 
Swamp Fever exists and can be transmitted by the inoculation of the 
blood of infected animals. Sarcosporidial spores were not seen, outside 
of their cysts, in any of the numerous smears and sections which were 
made from our animals ; and even although Sarcosporidia may possibly 
produce an intoxication,^^ they did not occur in our cases in sufficient 
numbers to account for the symptoms which existed. 
XIV. Conclusions. 
Our cases were too few in number for it to be possible to 
draw definite conclusions from them. Our results do not 
differ from those obtained by previous observers ; conse- 
quently, our observations will merely serve to confirm those 
of others who have preceded us in studying the disease. 
Swamp Fever is a disease of horses which is widely dis- 
tributed in the Western United States and in Western 
Canada. 
It is usually a chronic disease and is characterized by 
emaciation, weakness, irregular temperature and anemia. 
It is caused by an infecting agent which can be transmitted 
