86 LABORATORY BACTERIOLOGY 
EXERCISE XXXII 
TYPHOID AND PARACOLON BACILLI 
131. The bacillus of typhoid fever and 2. suipestifer resem- 
ble each other very closely morphologically and in certain of 
their cultural characters and biochemic properties. Like B. coli 
each of these organisms has several varieties. Several distinct 
varieties of B. suzpestifer have been described. 
Certain of the varieties of these species approach each other 
very closely, while others approach £. cod in their various man- 
ifestations. It is important, therefore, that the morphology 
and properties of each of these species should be carefully 
determined. The fact should be kept clearly in mind that 
while these two species and the colon bacillus resemble each 
other in certain directions, they are, so far as has yet been 
demonstrated, distinct species. The special methods of differ- 
entiation must be omitted from’ this elementary course. Read 
carefully the chapter on B. ¢yphosus in the text-books. 
132. Work for this exercise. Examine the plate cultures 
made from the intestine for the colon bacillus. 
Determine the approximate number of colonies on each 
plate. Note especially the number of colonies of &. cof and 
describe their appearance. 
Inoculate a tube of agar, one of milk, and a fermentation 
tube of glucose bouillon from one of the colonies. Study these 
cultures in the next exercise and compare them with the notes 
on cultures of 2. coi in these media. 
Examine and carefully describe the cultures of B. “phosus 
and B. paracolon. Note especially the reaction of the cul- 
tures in the fermentation tubes. Examine the bouillon culture 
of B. typhosus and the glucose bouillon culture of B. paracolon 
microscopically in hanging-drop and in stained cover-glass 
preparations. Describe the appearance of the bacteria. 
