200 ANTHRAX. 



tinguished the spontaneous and the communicated carbuncle of 

 man. The primary existence of anthrax in man was asserted by 

 Bayle in 1800 and by Davy la Chevrie in 1807. 



DESCRIPTION OF THE BACILLUS OF ANTHRAX. Rods 5-10 

 micromillimetres long, and 11.25 micromillimetres broad, and 

 threads made up of rods and cocci. The rods, as a rule, are straight, 

 only when they grow to a considerable length and meeting \vith re- 

 sistance they become curved. The rods and threads are round, and 

 with their ends truncated at right angles appear as though they 

 had been cut off obliquely. The interior, as long as fission does 

 not proceed, is perfectly homogeneous and absorbs aniline dyes 

 very readily. The development of spores in long undivided 

 threads, as we find them in fluid culture media, takes place at 

 regular intervals, where we find them as bright oval spots which 

 become more and more apparent, marking the direction of the rods. 

 Upon solid culture media the development of spores is preceded 

 by transverse segmentation of the rods. The cell-membrane of 

 each section finally becomes the membrane of the spore, each pole 

 of the spore presenting a small mass of protoplasm which can be 

 stained. 



STAINING. Cover-glass preparations of fluid specimens can be 

 stained with a watery solution of any of the aniline dyes. They 

 can be rapidly stained with a drop of fuchsin or gentian-violet, but 

 more satisfactorily by floating the cover-glass for twenty-four hours. 

 The preparations are dried and mounted in Canada balsam. The 

 spores are not stained by the ordinary methods. Tissue sections 

 are best stained by Gram's method, and after-stained with eosiu, 

 picrocarminate of ammonium. By double staining the rods are 

 seen to consist of a hyaline sheath with protoplasmic contents. 



CULTIVATION. a. G-elatin. If a nutrient medium of 5 to 8 

 per cent, of gelatin is inoculated, a whitish line develops in the 

 track of the needle puncture, and from it fine filaments spread out 

 on the sides. In a more solid nutrient gelatin, the growth appears 

 only as a thick, white thread. The culture liquefies the gelatin, 

 and the growth subsides as a white flocculent mass. 



b. Agar-agar. Cultures upon a sloping surface of nutrient 

 agar-agar form a viscous snow-white plaque. Without access of 

 air the culture does not grow, the bacilli being aerobic. 



c. Potato. Inoculation of sterilized potato yields a very char- 

 acteristic growth. The deep chamber, containing the potato, is 

 placed in the incubator, and in about thirty-six or forty-eight hours 

 a creamy, very faintly yellowish layer forms over the inoculated 

 surface, with usually a peculiar translucent edge. On removing 

 the cover of the damp chamber a strong, penetrating odor of sour 

 milk is emitted. 



