ILLUSTRATIONS. 



Fir:. 1. Chart of the changes in virulence of cholera strain No. 1. (To accom- 

 pany Series I.) 



2. Chart of the changes in virulence of cholera strain No. 2. (To accom- 



pany Series II.) 



3. Chart of the changes in virulence of cholera strain No. 3. (To accom- 



pany Series III.) 



4. Chart of the changes in virulence of cholera strain No. 4. (To accom- 



pany Series IV.) 



5. Chart of the changes in virulence of cholera strain No. 5. (To accom- 



pany Series V.) 



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