GERM-THEORY OF DISEASE. 347 
Schizophytes are merely varieties of harmless forms which have 
acquired special virulence is defended by many authorities. 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 results 
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 
