DIAGNOSIS OF ANTHRAX 319 



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 

 appearance, by a microscopical examination, and by cultivation. 

 The animal experiment is by far the most certain method of 

 diagnosis, a negative 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 are 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 two to three minutes. Tubes of melted 

 agar (6-9 c.c.) at 80 C. are then inoculated with J c.c. of the wash 

 and poured into Petri dishes (4-inch). The characteristic deep- 

 lying colonies (p. 308) should then be searched for after twenty 

 hours' incubation. Animals may be also inoculated. 



