172 SPECIAL BACTERIOLOGY 



in a U-shaped tube and centrifugalised, the tube is broken off at the 

 junction of the serum and corpuscles, and the drop of serum blown on 

 to a glass slide. The necessary quantity is sucked up to the first mark 

 on a special straight capillary tube, with another mark corresponding 

 to sixteen times the volume at the first mark. Bouillon is then sucked 

 up with the serum until the second mark is reached, and the whole 

 blown on to a glass slide, mixed, and again sucked up ; and the process 

 repeated two or three times to ensure thorough mixing. The emulsion 

 of typhoid fever bacilli is prepared by taking a small platinum loop full 

 of a culture not more than twenty-four hours old, grown on rather dry 

 agar, and carefully rubbing it up against the side of the glass tube con- 

 taining 1 c.c. of bouillon with 1 drop of the bouillon, and subsequently 

 mixing it with the whole quantity. A control preparation is examined 

 microscopically to make sure there are not any, or very few pre-existent 

 clumps in the emulsion. A small drop of the diluted serum is then placed on 

 a cover-glass, and a drop, as near the same size as possible, from the typhoid 

 emulsion mixed with it, and a hanging-drop specimen prepared in the 

 usual manner. Microscopically examined, the bacilli will be observed 

 to gradually form groups of three or four, which, with the addition of 

 other bacilli, constantly increase in size, until the majority are in c clumps ' 

 with impaired or lost motility. If the reaction is marked within thirty 

 minutes the case is one of enteric fever, but without great experience 

 it is impossible to say that the absence of this reaction negatives such a 

 diagnosis. In negative results more than one examination should be 

 made, for it occasionally, although rarely, occurs that probably from 

 experimental errors, such as varying quality of bouillon, etc., that the 

 reaction is seen on one day and not on another. 



Wyatt Johnston has published results got by using a watery solution 

 of long-dried blood serum from typhoid patients. The crust of blood 

 is covered with a drop of water, and on standing for one or two minutes 

 a drop of this is mixed with one loopful of a typhoid culture, a second 

 loopful being added later. The agglutinative action is seen as in the 

 ordinary way of doing Widal's reaction. 



In 1897, the author, whilst working this test in California with Prof. 

 Kerr of the California University, found that quite good results were got 

 by using filter paper to absorb the blood, and then making a watery 

 solution as above. This method was much more convenient for most 

 ordinary cases than the capillary tubes with ceiitrifugalisation. 



The Investigation of Water for Typhoid Bacilli. This is essential in all 

 outbreaks of typhoid fever, for water has been repeatedly shown to be 

 the vehicle of infection. For this examination, carbolic acid is added to 

 the water in the proportion of 0'05 to 0'25 per cent., as this addition 

 serves to inhibit the development of the ordinary liquefying water 

 bacteria, while the typhoid and some allied forms grow in presence of a 



