BACILLUS ANTHRACIS 301 



During the early part of last century much attention was paid to 

 it, and, with a view to finding out its nature and means of spread, 

 various conditions attaching to its occurrence, such as those of soil and 

 weather, were exhaustively studied. Pollender in 1849 pointed out that 

 the blood of anthrax animals contained numerous rod-shaped bodies 

 which he conjectured had some causal connection with the disease. In 1863 

 Davaine announced that they were bacteria, and originated the name 

 bacillus anthracis. He stated that unless blood used in inoculation 

 experiments on animals contained them, death did not ensue. Though 

 this conclusion was disputed, still by the work of Davaine and others 

 the causal relationship of the bacilli to the disease had been nearly 

 established when the work of Koch appeared in 1876. This constituted 

 that observer's first contribution to bacteriology, and did much to clear up 

 the whole subject. Koch confirmed Davaine's view that the bodies were 

 bacteria. He observed in the blood of anthrax animals the appearance 

 of division, and from this deduced that multiplication took place in the 

 tissues. He observed them under the microscope dividing outside the 

 body, and noticed spore formation taking place. He also isolated the 

 bacilli in pure culture outside the body, and, by inoculating animals with 

 them, produced the disease artificially. In his earlier experiments he 

 failed to produce death by feeding susceptible animals both with bacilli 

 and spores, and as the intestinal tract was, in his view, the natural path 

 of infection, he considered as incomplete the proof of this method of the 

 spontaneous occurrence of anthrax in herds of animals. Koch's obsterva- 

 tions were, shortly afterwards, confirmed in the main by Pasteur, 

 though controversy arose between them on certain minor points. 

 Moreover, further research showed that the disease could be produced 

 in animals by feeding them with spores, and thus the way in which the 

 disease might spread naturally was explained. 



The Bacillus Anthracis. Anthrax as a disease in man is of 

 comparative rarity. Not only, however, is the bacillus anthracis 

 easy of growth and recognition, but in its growth it illustrates 

 many of the general morphological characters of the whole group 

 of bacilli, and is therefore of the greatest use to the student. 

 Further, its behaviour when inoculated in animals illustrates 

 many of the points raised in connection with such difficult 

 questions as the general pathogenic effects of bacteria, immunity, 

 etc. Hence an enormous amount of work has been done in 

 investigating it in all its aspects. 



If a drop of blood is taken immediately after death from an 

 auricular vein of a cow, for example, which has died from 

 anthrax, and examined microscopically, it will be found to 

 contain a great number of large non-motile bacilli. On making 

 a cover-glass preparation from the same source, and staining with 

 watery methylene-blue, the characters of the bacilli can be better 

 made out. They are about 1*2 /x thick or a little thicker, and 6 

 to 8 \i long, though both shorter and longer forms also occur. 

 The ends are sharply cut across, or may be slightly dimpled so 

 as to resemble somewhat the proximal end of a phalanx. Their 



