METHODS OF EXAMINATION 359 



on the bacteria, and that thus the effects are to be traced to 

 opsonic action. With regard to the formation of the protective 

 substances, it is stated that the spleen and bone-marrow are 

 richer in these than the blood fluids. In this connection an 

 interesting fact may be mentioned, namely, that Roger and 

 Gamier found evidence of the liver and spleen having special 

 capacities for killing anthrax bacilli ; an otherwise fatal dose 

 could be introduced into the portal vein or the splenic artery 

 without causing death. It has been thought that the capsule 

 of the anthrax bacillus is a defensive mechanism against 

 bactericidal and bacteriolytic capacities in an infected animal. 

 It is stated that capsulation renders the bacillus less susceptible 

 to phagocytosis. In certain anti-anthrax sera precipitins for 

 the bacilli are stated to be present, but the investigation of such 

 sera by the complement deviation method has not furnished 

 convincing evidence of the presence of anti- bodies. 



Methods of Examination. These include (a) microscopic 

 examination ; (6) the making of cultures ; (c) test inoculations \ 

 and (d) Ascoli's precipitin reaction. 



(a) Microscopic Examination. In a case of suspected 

 malignant pustule, film preparations should be made from the 

 fluid in the vesicles or from a scraping of the incised or excised 

 pustule, and stained with a watery solution of methylene-blue 

 and also by Gram's method. By this method practically con- 

 clusive evidence may be obtained ; but sometimes the result 

 is doubtful, as the bacilli may be very few in number. 

 McFadyean's methylene-blue method (p. 343) should also be 

 applied. In all cases confirmatory evidence should be obtained 

 by culture. Occasionally bacilli are so scanty that both film 

 preparations made from different parts and even cultures may 

 give negative results, and yet a few bacilli may be found when 

 a section of the pustule is examined. It should be noted that 

 the greatest care ought to be taken in manipulating a pustule 

 before excision, as the diffusion of the bacilli into the sur- 

 rounding tissues may be aided and the condition greatly aggra- 

 vated. The examination of the blood in cases of anthrax in 

 man usually gives negative results, with the exception of very 

 severe cases, when a few bacilli may be found in the blood 

 shortly before death, though even then they may be absent. 



(6) Cultivation. A small quantity of the material used for 

 microscopic examination should be taken on a platinum needle, 

 and successive strokes made on agar tubes, which are then 

 incubated at 37 C. At the end of twenty-four hours anthrax 

 colonies will appear, and can be readily recognised from their 



