TYPHOID FEVER. 497 



doubtful cases of typhoid fever having been desired for a 

 long time, this offer met with ready acceptance, and it 

 was not long before a large number of cases had been 

 studied and the success of the measure shown to be 

 complete. Indeed, the outcome of Johnston's work was 

 the establishment, at the laboratory of the Board of 

 Health of the Province of Quebec, and later at most 

 public laboratories in this country, of a system of free 

 public examinations, by which the physicians of the 

 larger cities and towns can have their diagnoses con- 

 firmed. 



The paper upon which the blood is dried is moistened 

 with germ-free water, and a drop of the solution placed 

 upon a cover-glass which has just been passed through a 

 flame. A drop of a bouillon culture, or of a watery sus- 

 pension of an agar-agar culture of the typhoid bacillus, 

 is mixed with it, the cover placed upon a concave slide 

 prepared with vaselin so as to make a hanging drop, 

 and is then examined under a dry lens of moderate power 

 (one-fourth or one-fifth inch). This was Johnston's tech- 

 nic. Wesbrook, of Minneapolis, endeavored to improve 

 it by having the blood drops dried upon weighed pieces 

 of tin-foil, prepared for the purpose in the laboratory. 

 The advantage of this is that the exact weight of the 

 blood secured can be determined, and accurate dilution 

 made for the occasional cases requiring them. 



Cabot has suggested the use of the medicine-dropper: 

 he secures blood from the finger and drops it into a recep- 

 tacle, and afterward follows it by a given number of drops 

 of bouillon-culture from the same medicine-dropper. In 

 our work we have not found it easy to do this, and it 

 is disadvantageous in that it must be performed at the 

 bedside. 



Some men have successfully employed the pipet used 

 for counting leukocytes. This seems excellent for bed- 

 side work. 



Delepine has suggested a method that can be employed 

 both in the laboratory and at the bedside. A drop of blood 

 32 



