172 



MICRO-ORGANIS^IS AND DISEASE [ch. ix 



they are invariably killed, but not their spores. Even heat- 

 ing them from half an hour to several hours at a temperature 

 above 55° or 60° C. kills them. P'reezing also kills them, 

 but not their spores. Carbolic acid, corrosive sublimate, 

 thymol, &c., kill them. 



The formation of spores and the germination of these 



Fig. 46 — Threads of TiAcir-Li (B. Anthracis) showing im Parts, or as a 



WHOLK, THE EMI'TY SHEATH WITHOUT ANY StaINED BaCILLAKV PkQTO- 

 PLASM. 



X 600. 



have been already described in a former chapter, and it now 

 remains to describe the methods of staining them. When 

 spores, either free or in bacilli, are stained in the usual way 

 in film specimens, the spores do not take the stain, but 

 remain conspicuous as clear oval bodies ; in order to make 

 them take the dye it is necessary, after drying in the usual 



