Isolation 63 1 



When sections of tissue are to be stained for the demonstration of 

 the typhoid bacilli, the best method is to allow them to remain in 

 Loffler's alkaline methylene blue for from fifteen minutes to twenty- 

 four hours, then wash in water, dehydrate rapidly in alcohol, clear 

 up in xylol, and mount in Canada balsam. Ziehl's method also 

 gives good results: The sections are stained for fifteen minutes in a 

 solution of distilled water, 100, fuchsin i, and phenol 5. After 

 staining they are washed in distilled water containing i per cent, of 

 acetic acid, dehydrated in alcohol, cleared, and mounted. In such 

 preparations the baciUi 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. 



Fig. 256. — Bacillus tjrphi abdominalis ; superficial colony two days old, as seen 

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



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 

 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 bacilU can also be secured from the alvine discharges of 



