xii.] Anthrax. 133 



been observed. Thus it is stated by Koch and his colleagues 

 that the Bacillus which is only strong enough to kill mice 

 fills the capillaries, especially of the lungs, in the form of 

 long filaments, which may often be followed continuously from 

 the capillaries into the larger microscopic vessels, while the 

 more virulent Bacillus is usually present in the capillaries in the 

 form of short rods. 



In Prazmowski's observation the difference between the viru- 

 lent and attenuated forms was, that the rods of the latter kind 

 were motile during several generations, though their motion was 

 slow and dragging in comparison, for example, with that of the 

 hay-bacillus, and that they not only form flakes at the bottom 

 of the nutrient solution which is clear above them, but also rise 

 in it and make it turbid, and form on its surface ' thickish dirty- 

 white films of a slimy consistence.' Exactly the same appear- 

 ance has been observed by myself in meat-extract-solution; 

 there the rods even up to the time of forming their spores were 

 much less united into long filaments than in the virulent forms, 

 and in the surface-films they lay in every direction, and were 

 densely and irregularly compacted together into a felted mass. 

 This mode of grouping is in appearance so unlike that of the 

 common Bacillus, that we are naturally led to assume that we 

 are dealing with a form very like Bacillus Anthracis, but yet 

 specifically distinct from it, which has not allowed the latter to 

 thrive in the solution, the Bacillus perhaps of Koch's malignant 

 oedema ; but the harmlessness of this form, even in the case of 

 small rodents, is against this assumption. 



Buchner undoubtedly observed the same phenomenon, when 

 he grew Bacillus Anthracis through several generations in nu- 

 trient solutions composed of i per cent, of meat-extract, with or 

 without the addition of sugar and peptone, and at a temperature 

 of 35-3 7 C., and kept the cultures in constant movement by 

 help of a rocking-apparatus in order to secure the largest 

 possible supply of oxygen. The products of the cultivation 

 gradually assumed the characters of Prazmowski's modified form. 



