THE MICROBES OF HUMAN DISEASES. 203 
Ferran regards this peronospora as the infectious 
agent of cholera. Yet it seems extraordinary that 
such a remarkable polymorphism should have escaped 
the observation of Koch and of the numerous micro- 
Figs. 88, 89, 90.—Evolution of cholera microbe (Peronospora Ferrant: Ferran): 
1, Cholera microbe (Bacillus komma), discovered by Koch. 2. Spiral form of 
pacillus, transferred from gelatine to an infusion. 3. Degeneration of spiral 
form after a series of successive cultures. 4. Cholera microbe (Peronospora 
ant): develop of oogonium on the spirilla and straight filaments. 
5. The oogonium is filled with granules which centre in a point k, and it is then 
converted into an oosphere ; m, pollinidium on fertilizing organ. 6. The cosphere 
is converted into mulberry-shaped and comma-shaped bodies. 
graphists who have made various cultures of the 
comma bacillus. It is difficult not to suppose that 
some negligence or error has vitiated Ferran’s re- 
