1923] Kessel: Infection with Intestinal Amoebae 405 



Stale bread was soaked in a solution of water saturated with the 

 magnesium sulphate. Hungry rats usually ate this mixture readily, 

 though the mice often refused to eat it until they had been offered 

 nothing else for several days. If the rats ate readily of the bread and 

 salts at 6 p.m., a sufficient quantity of semi-fluid material was assured 

 for examination during the next day. Rats which gave no reaction 

 from the salt the morning after being fed the prepared bread were 

 placed together in a separate cage and redosed, and were regarded 

 as unexamined rats. Rats which gave a positive reaction to the 

 purgative were given a lighter dose of salt the second night. A second 

 examination of faecal material was made the following day, after 

 which the animals were autopsied and examination was made of the 

 intestinal contents at different levels of the digestive tract. 



In making the smears a drop of normal salt solution was placed 

 near one end of the slide and about half an inch toward the middle 

 of the slide was placed a drop of Donaldson's iodine-eosin stain. The 

 faecal material was then smeared, first in the saline portion and then 

 in the iodine-eosin portion. In placing the cover glass on the smear, 

 contact was made first with the saline half of the smear. The motile 

 forms are easily detected in the normal saline solution and the cysts 

 more easily seen in the iodine-eosin. Cover glasses 12 mm. square 

 were used and two smears were made on the same slide. A 5X 

 ocular was used first with a 16 mm. objective for determining the 

 presence of the organisms. Then the 4 mm. objective was used for 

 more detailed study and for determining the species of organism 

 present. 



As the writer's investigation concerned amoebae only, no account 

 was taken of other Protozoa in the first series of animals examined. 

 In the second series examined other Protozoa were noted when present. 

 Results from the examination of 128 rats are shown in table 2. 



From the above table it will be noted that in one hundred and 

 twenty-eight rats examined, amoebae were found in the caecum in 

 only four rats where they had not been detected previously in the 

 faeces. Three of these cases had been examined on one day only 

 and the amoebae probably would have been detected had a second 

 examination been made. The fourth infection in the caecum only 

 was a very light infection. The four cases of Trichomonas found in 

 the caecum only were also exceptionally light infections. Amoebae 

 were found twice in the ileum while Trichomonas was found four 



