548 BACTERIOLOGY. 



pulmonary forms, the latter being known as " wool- 

 sorter's disease." 



Owing to the fact that anthrax was the first infec- 

 tious disease which was shown to be caused by a specific 

 micro-organism, and to the close study which it received 

 in consequence, this disease has probably contributed 

 more to our general knowledge of bacteriology than 

 any other infectious malady. 



Pollender observed in 1849 that the blood of animals 

 suffering from splenic fever always contained minute 

 rod-shaped bacteria. Davaine, in 1863, announced to 

 the French Academy of Sciences the results of his in- 

 oculation experiments, and asserted the etiological rela- 

 tion of the micro-organism to the disease with which 

 his investigation showed it to be constantly associated. 

 For a long time this conclusion was energetically op- 

 posed until, in 1879, Pasteur, Koch and others estab- 

 lished its truth by obtaining the bacillus in pure cultures 

 and showing that the inoculation of these cultures pro- 

 duced anthrax in susceptible animals as certainly as did 

 the blood of an animal recently dead from the disease. 



Morphology, Slender, cylindrical, non-motile rods, 

 having a breadth of \p to 1.25//, and ranging from 2 

 or 3// to 20 or 25// in length. They vary thus very 

 much in their length. Sometimes short, isolated rods 

 are seen, and, again, shorter or longer chains or threads 

 made up of several rods joined end to end. In suitable 

 culture media very long, flexible filaments may be 

 observed, which are frequently united in twisted or 

 plaited, cord-like bundles. (See Fig. 71 and Fig. 13, 

 p. 47, and Fig. 17, p. 207.) These filaments in hang- 

 ing drop cultures, before the development of spores, 

 appear to be homogeneous or nearly so; but in stained 



