24 CLINICAL BACTERIOLOGY. 



extremely resistant ; much more so than the mature bacteria 

 themselves. They withstand for years drying and all at- 

 mospheric influences. Nature possesses but one agency 

 capable of rendering them harmless namely, the direct 

 action of the rays of the sun, insolation. In order to de- 

 stroy the spores of anthrax-bacilli, which are not even 

 among the most resistant, exposure to dry heat of 140 C. 

 (284 F.) for three hours, or to steam of 100 C. (212 F.) 

 for a few minutes, is necessary. Far greater resistance is 

 displayed by the spores of Fliigge's peptonizing milk-bac- 

 teria, as well as by some members of the group of hay- 

 bacilli and potato-bacilli, which may survive exposure to 

 live steam for five, six, and even for sixteen hours. 



The question as to the existence of pleomorphic bacteria 

 of varied form has not yet been decided with certainty. 

 Pleomorphism has been conceded by some authorities to 

 the proteus obtained by Hauser from decomposing fluids. 

 It is, however, quite probable that the spheric bodies in the 

 cultures of the proteus result in consequence of the retarded 

 growth in the presence of progressive division. If the ac- 

 tinomyces are included among bacteria, there is no alterna- 

 tive but to admit the occurrence of pleomorphism. The 

 actinomyces-fungus, however, is no longer grouped by 

 most authorities among bacilli. Kruse, in Fliigge's " Text- 

 book," makes a special group of streptothricece, of which 

 the actinomyces may be considered the most important 

 representative. These streptothriceae stand midway between 

 the filamentous fungi and the true bacteria, and they are 

 characterized by the formation ol filaments and especially 

 by the ramification resulting in consequence of their ger- 

 mination. In old cultures the filaments break up into 

 bodies resembling bacilli, spirilla, and cocci, and there is 

 thus yielded an appearance of pleomorphism. A further 

 peculiarity of the streptothriceae is the formation of air- 

 hyphae that give rise to germ-cells (spores) by segmentation. 

 These are probably not analogous to bacterial spores, as 

 they are destroyed by exposure for five minutes to a tem- 

 perature of 75 C. (167 F.). Nevertheless, they with- 

 stand higher degrees of temperature than the filaments, 

 which undergo destruction at 60 C. (140 F.). As the 

 result of personal investigation, we are of the opinion that 

 the actinomyces-group represents a subdivision of the fila- 

 mentous fungi. 



