264 A MANUAL OF BACTERIOLOGY 



by the opsonic method, using anthrax spores, may be of value. 

 At the same time cultivations on agar and gelatin should be pre- 

 pared, and may yield positive results when the microscopical 

 examination has been negative. In the later stages of the disease 

 the bacilli may be difficult to find, even in sections. 



In all cases of doubt a guinea-pig or mouse should be inoculated 

 subcutaneously with the material, and if the animal dies the diagnosis 

 of anthrax may be confirmed by the characteristic appearances, by 

 a microscopical examination, and by cultivation. The animal 

 experiment is by far the most certain method of diagnosis, a nega- 

 tive result being nearly as valuable as a positive one. 



N.B. It must be noted that both cultivation and inoculation 

 experiments may fail to give positive results if the material be old 

 or putrid. 



(3) In -wool, hair, etc. Eurich (loc. cit.) recommends a suitable 

 quantity of the material to be placed in a flask with 50 c.c. to 

 100 c.c. of boiled water to which 3-5 c.c. of 5 per cent, solution of 

 caustic potash is added. If much blood-stained, the mixture is 

 allowed to stand at 37 C. for several hours. It is then poured into 

 a flat dish and the wool or hair is well teased. The mixture is then 

 heated to 80 C. for 2-3 minutes. Tubes of melted agar (6-9 c.c.) 

 at 80 C. are then inoculated with ^ c.c. of the wash and poured into 

 Petri dishes (4 inch). The characteristic deep-lying colonies 

 (p. 253) should then be searched for after twenty hours' incubation. 

 Animals may also be inoculated. 



