ANTHRAX. 273 



and that the envelope is used up during its 

 growth. 



At 35 C. (95 Fahr.) spores make their ap- 

 pearance at the end of twenty-four hours. At a 

 lower temperature (28 C.) the growth of the rods 

 into filaments takes place more slowly, and the 

 formation of spores is not completed in less than 

 thirty-six to forty-eight hours. At 42 to 43 C. 

 the rods grow and multiply by fission, but spores 

 are no longer formed. No development occurs 

 at temperatures below 12 C. (53.6 Fahr.). In 

 Fig. 3, Plate VIII., a spore-bearing filament is 

 seen in the centre of the field, while scattered 

 about are liberated spores and detached segments 

 of the filaments. The amplification is 500 diame- 

 ters, and the specimen is from a culture made 

 in chicken bouillon. 



A statement relating to the source of the ma- 

 terial which furnished specimens for my photo- 

 micrographs, Plate VIII., may not be uninterest- 

 ing, as illustrating the facts already given. 



While pursuing certain experimental inquiries 

 in the biological laboratory of Johns Hopkins 

 University during the summer of 1881, Professor 

 Martin placed in my hands a small tube just re- 

 ceived by him from Dr. Burdon-Sanderson, of 

 London. In a letter accompanying this, Burdon- 

 Sanderson says: "I send you the material I 

 started from in the last experiments I made upon 

 the subject (anthrax). It was then five years 

 old, and consequently is now seven or eight. I 



