THE ORIGIN OF MICROBES 103 



as far as we know at present, from spores, etc., of 

 the same kind (Cohn). 



Concerning the doctrine of pleomorphism, it may 

 be stated that Lankester, 1 Van Tieghem, Zopf, 

 Cienkowski, Billroth, Neelsen, Hauser, and others 

 have noticed that certain microbes pass through 

 various phases during their life-histories. And 

 Sattler, Gravitz, and Blichner, believe that they have 

 transformed certain non-pathogenic microbes into 

 pathogenic forms by simply cultivating the former 

 in different media or under different physical condi- 

 tions. For instance: Sattler 2 states that he has 

 transformed the non-pathogenic Bacillus subtilis 

 into a pathogenic form, capable of producing 

 infectious ophthalmia, by cultivating the microbes 

 (at 35 C.) in an infusion of jequirity seeds. Gravitz 

 believed that he had transformed the non-pathogenic 

 moulds Aspergillus glaucus, Penicillium glaucum 

 into pathogenic forms by cultivating them in 

 alkaline media at about 40 C. Biichner states 

 that he has transformed Bacillus subtilis into 

 Bacillus anthracis and vice versd : ' that by successive 

 cultivation of Bacillus anthracis under constant 

 variation of the nutritive material, he saw it assume 

 the morphological and physiological characters of 

 Bacillus sultilis! 



Klein, Koch, Cohn and others do not accept the 

 theory of pleomorphism, or the transformation of 

 microbes ; and Klein 3 has proved most conclusively 



1 Quarterly Journal of Microscopical Science, 1873, p. 408. 



- Wiener Medic. Wochenschrift, 1883. 



3 Micro-Organisms and Diseate, pp. 207-231 (3d ed.). 



