102 ANTHRAX 
careful work of Fischoeder has clearly pointed out the difficulties in 
this direction. Secondly, errors may occur because of the presence of 
what are called pseudo-anthrax bacteria from which a differentiation 
is not alwayseasy. Fitch pointed out that these organisms could not 
be differentiated from Bact. anthracis from agar or gelatin cultures. 
Pokschischewsky has studied their biology and shown their very close 
resemblance, in certain particulars, to Bact. anthracis. He divides 
these organisms according to their growth on agar, gelatin and potato. 
into two types, namely, pseudo-anthrax and anthraxoid. Microscop- 
ically the presence of an organism resembling that of anthrax, often 
found in tissues some hours old, may be mistaken for that of anthrax. 
The diagnosis bacteriologically requires the isolation of the specific 
bacterium and its identification by cultural methods or animal inocu- 
lation. 
Differential stain. M’Fadyean has described a peculiar staining 
reaction, first pointed out by Heins, which he considers of value for 
the microscopic diagnosis of this disease. The reaction is in evidence 
when films of blood, exudates, or tissue juice containing the bacteria 
are stained with a simple aqueous solution of methylene blue. The 
method as applied to blood is as follows: 
Place a drop of the blood on a clean slide. The size of the drop should be about 
2 mm. in diameter. It is spread quickly with a platinum needle untilit covers an 
area about 12 mm. in diameter. Protect from dust and allow the slide to remain until 
all evidence of moisture has disappeared. When dry, heat the preparation by lowering 
it film upwards into the flame of a Bunsen burner or an alcohol lamp for a second. 
Repeat this three times or until the glass is too hot to be borne by the skin in the palm. 
of the hand. Allow the slide to cool and then cover the film with 1 per cent. aqueous 
solution of methylene blue. After a few seconds pour off the free stain and wash the 
slide thoroughly in tap water. Dry the slide by pressing it gently between two layers 
of bibulous paper, and then more thoroughly by holding it in the current of hot air 
above the Bunsen flame. Finally, mount in Canada balsam. 
The microscopic examinations (x 800 to 1000) will show an occasional leucocyte and 
the anthrax bacteria. There will appear no other visible formed elements. The nuclei 
of the corpuscles generally exhibit a greenish-blue tint, the anthrax rods are stained 
blue. The intensity of the stain depends upon the length of time after death before the 
films were made. Usually the segment character of all but the shortest rods will be 
apparent. If they are deeply stained this is not very distinct. The peculiarity in the 
reaction lies in the color of the amorphous material which is present between and around 
the bacteria. This material presents itself under the form of coarse or fine granules of a 
violet or reddish-purple color, which is in sharp contrast to the tint of the bacteria or 
cell nuclei, especially with brilliant lamp or gas light. These violet granules differ a 
good deal in form and size; sometimes they are very minute, and at others coarsely 
granular. When the bacteria are arranged in clumps the violet material is often in 
