234 TODD AND WOLBACH. ^ 
During the summer of 1908 one of us spent five weeks in traveling * 
through the Canadian Middle West in search of cases of Swamp Fever. 
The trip was made in July, when cases are exceptionally scarce and only 
four horses which seemed to be certainly suffering from the disease were 
found. In three of these horses the diagnosis was probably correct ; in 
one it was doubtful. In the three animals, which were probably infected, 
anemia was marked ; one of them had only 2,000,000 red cells, 8,000 - 
white cells, and a hemoglobin count of 35 per cent. In one horse auto- 
agglutination of the red cells in fresh coverslip preparations of blood was 
very marked ; it was also present in the Grey Gelding. The blood of all 
these three animals was carefully examined in fresh preparations, in 
smears, and by centrifugalization. Nothing resembling a parasite was 
seen in any of them. 
Although previous observers had examined the blood of 
animals suftering from Swamp Fever during long periods 
and at all hours of the day and night, we made extremely 
careful examinations of the blood of all of our animals 
because the symptoms of Swamp Fever are precisely those 
which are present in many trypanosome infections, and 
experience has shown that, as — for example — in Dourine 
and, sometimes, in infections by Trypanosoma dimorphon, 
an examination extending over months may fail to reveal 
the presence of the parasite which is causing the death of 
the animals infected by it. In spite of our search no such 
parasite was found in any of our horses or in any of the 
animals inoculated from them. 
At the autopsies of the horses infected with Swamp Fever, 
and of the various experimental animals of all sorts which 
were inoculated from them, smears were made from all of 
the tissues and body fluids. These smears were stained by 
a modification of Romanowsky's method and they were 
examined with extreme care, on a mechanical stage, with 
the highest magnifications (Zeiss Comp. No. 8 ocular; 1.5 
millimeters Apo. objective). No appearances which could 
be thought to be parasites were seen in any of them. 
Many smears, particularly those from the liver, lymph 
glands, and spleen, contained peculiar bodies similar to 
* Thanks are due to the Canadian Pacific Railway for the possibilities given us on 
this occasion. 
