110 MARSHALL. 



into another guinea pig and at intervals a few drops of peritoneal fluid 

 were drawn off and plated. One one-thousandth cubic centimeter of the 

 fluid drawn after half an hour contained two colonies, and the fluid 

 drawn after three and one-half and after twenty-four hours was sterile, 

 while a control plate made with one four hundred thousandth of the 

 exudate used for inoculation showed thirty-eight colonies, and another 

 control with one four thousandth cubic centimeter developed about two 

 hundred and seventy-six colonies. 



This must be interpreted as proving that the bacteria in the exudate 

 were no longer viable in the guinea pig's peritoneal cavity, although 

 still viable on artificial media. 



Eeference to the table will show that the cultures and morphology of 

 the peritoneal bacteria were not typical, although cholera-like organisms 

 were found. However, the fact that in the inoculations of November 27 

 the minimal fatal dose was 0.0001 cubic centimeter and that the exudate 

 from this animal gave a surface growth on peptone, indicate that the 

 cholera vibrios were still living up to the next to last of the series, and 

 it is a reasonable presumption that they lived up to the last inoculation. 

 This finding contrasts rather strikingly with the condition observed at 

 the close of Series I. 



Series IV, inoculated from an autopsy toward the close of the epidemic, 

 showed such low pathogenic power that 0.1 cubic centimeter of a 24-hour 

 pejttone culture did not kill a guinea pig. After Series V had been 

 continued four days, the virulence fell op. the fifth below 0.01, and the 

 series was discontinued. With Series VI also the virulence rose to 0.01, 

 then fell. 



These experiments show that there is a great difference between the 

 individual strains of cholera, and that this difference is a deep-seated one, 

 possibly fundamental. They also demonstrate the possibilities of varia- 

 tion with cholera to be enormous ; for here we have the fatal dose for 

 medium-sized guinea pigs one fifty-thousandth and one ten-thousandth 

 of a cubic centimeter of exudate, which minute quantity is not made up 

 entirely of bacteria but contains also serum and cellular contents, while 

 the average standard for cholera as given by Kolle is one-tenth of a 

 platinum loopful, which would be approximately 2 milligrams. 



DIFFERENCES DURING ROUTINE EXAMINATIONS. 



It. may be well to refer briefly at this point" to certain differences which 

 have been noted during the routine examinations upon cases suspected of 

 cholera. In the epidemic of August, 1907, routine examinations were 

 made, according to custom, of the bowel contents of all cases supposed 

 to have died of cholera and of the stools of patients supposed to have 

 been suffering from this disease. At that time Dr. Ealph T. Edwards, 



