GERM-THEORY OF DISEASE. 347 



Schizophytes are merely varieties of harmless forms which have 

 acquired special virulence is defended by many authoi'ities. Dr. H. 

 Buchner, of Munich, has described the conversion by artificial cul- 

 ture of the ordinary Bacillus of Hay-Infusion into the virulent 

 Bacillus of Anthrax and vice versa. Although many careful ob- 

 servers hesitate to recognize the value of his experiments, there can 

 be no doubt that the virulence of the Bacillus of Anthrax may be 

 " attenuated" by cultivation under certain conditions. Such attenu- 

 ated virus has been employed by Pasteur for the protective innocu- 

 lation of sheep and cattle against Anthrax. Although the residts 

 obtained have not been so satisfactory as could be desired, yet the 

 establishment of the principle is a great step in advance in the 

 fighting of the infectious diseases. 



The physiological inconstancy of the Schizophytes is likely to 

 prove as great a stumbling block in the way of their classification as 

 their inconstancy of form. It has been proposed, however, to 

 arrange them in three groups : colour-producing (Chromogenic), 

 fermentation-producing (Zymogenic), and disease-producing (Patho- 

 genic) forms. 



To the Chromogenic forms belong the Micrococcus prodigiosus, 

 which forms a red incrustation on bread, besides other Micrococci 

 which produce the characteristic colours of " blue milk," " blue pus," 

 " red sweat," &c. Higher members of the Schizophyte group may 

 also be Chromogenic. 



A very large number of forms are recognized as Zymogenic. The 

 yeast plant (Saccharomyces) and its allies, although reproducing by 

 budding and not by division, have nevertheless many points in 

 common with the true Schizophytes, and are conveniently considered 

 along with them. Several species of Saccharomyces are known 

 capable of producing the alcoholic fermentation, but the amount of 

 sugar destroyed and alcohol produced appear to be different for the 

 different species. One form, S. mycoderma, is so avid of oxygen that 

 if it should be formed in wine, the alcohol undergoes slow combus- 

 tion, and eventually little but water is left behind. To the 

 Zymogenic group, however, belong many true Schizophytes ; such 

 are the ferments of the acetic, lactic, butyric and viscous fermenta- 

 tions, as well as many others to which chemists and biologists are 

 only now turning their attention. So putrefaction is now generally 

 recognized to be a form of fermentation, complex on account of the 



