452 BACTERIOLOGY. 



of sterile bouillon, and this mixture is distributed over 

 a series of Drigalski-Conradi plates. Ficker advises 

 when possible the use of a centrifuge for the separation 

 of the precipitate, as he believes the results are likely 

 to be more satisfactory. 



ISOLATION OF BACILLUS TYPHOSUS FROM CADA- 

 VERS. The spleen of a patient dead of typhoid fever is 

 the most reliable source from which to obtain cultures 

 of the typhoid bacillus for study. But it must always be 

 remembered that the same channels through which the 

 typhoid bacillus gains access to this viscus are likewise 

 open to other organisms present in the intestines, and 

 for this reason bacillus coli, a normal inhabitant of the 

 colon, may also be found in this locality. 



NOTE. Obtain a pure culture of typhoid bacilli, and 

 from this make inoculations upon a series of potatoes 

 of different ages and from different sources. Do they 

 all grow alike ? 



Before sterilizing render another lot of potatoes slightly 

 acid with a few drops of very dilute acetic acid ; render 

 others very slightly alkaline with dilute caustic soda. 

 Are any differences in the growths noticeable ? 



Make a series of twelve tubes of peptone solution to 

 which rosolic acid has been added. Inoculate them all 

 with as nearly the same amount of material as possible 

 (one loopful from a bouillon culture into each tube) ; 

 place them all in the incubator. Is the color-change, 

 as compared with that of the control-tube, the same in 

 all cases. 



Compare the morphology of cultures of the same age 

 on gelatin, agar-agar, and potato. 



Select a culture in which the vacuolations are quite 



