Cultivation 591 



preparations the bacilli are always found in scattered groups, which 

 are easily discovered, under a low power of the microscope, as 

 reddish specks, and readily resolved into bacilli with the oil-im- 

 mersion lens. 



In bacilli stained with the alkaline methylene-blue solution, 

 dark-colored dots (Babes-Ernst or metachromatic granules) may 

 sometimes be observed near the ends of the rods. 



Isolation. The bacillus can be secured in pure culture from an 

 enlarged lymphatic gland or from the splenic pulp of a case of typhoid. 



As the groups of bacilli are sometimes widely scattered through- 

 out the spleen, E. Frankel recommends that as soon as the organ 

 is removed from the body it be wrapped in cloths wet with a solution 

 of bichlorid of mercury and kept for three days in a warm room, in 

 order that a considerable and massive development of the bacilli 



Fig. 249. Bacillus typhi abdominalis ; superficial colony two days old, as seen 

 upon the surface of a gelatin plate. X 20 (Heim). 



may take place. The surface is then seared with a hot iron and ma- 

 terial for cultures obtained by introducing a platinum loop into the 

 substance of the organ through the sterilized surface. 



Cultures may be more easily obtained from the blood of the 

 living patients. (See " Blood culture," under the section "Bacterio- 

 logic Diagnosis.") 



The bacilli can also be secured from the alvine discharges of 

 typhoid patients during the second and third weeks of the disease. 



Cultivation. The bacillus grows well upon all culture-media 

 under both aerobic and anaerobic conditions. 



Colonies. The deep colonies upon gelatin plates appear under the 

 microscope of a brownish-yellow color and spindle-shape, and are 

 sharply circumscribed. When superficial, however, they become 

 larger and form a thin, bluish, iridescent layer with notched edges. 

 The superficial colonies are often described as resembling grapevine 

 leaves in shape. The center of the superficial colonies is the only 



