vii.] PRODUCTION OF CHOLERA. 135 



ought to yield a most formidable host of descendants, 

 and grave doubts must arise as to the tenability of Koch's 

 explanation. 



But to continue. In order to produce a condition similar 

 to the one in the above single successful experiment on the 

 guinea-pig, Koch injected tincture of opium into the peri- 

 toneal cavity after the introduction of the sodium carbonate 

 and the cultivation of the comma-bacilli : this answered well 

 for achieving positive results. Immediately after the adminis- 

 tration of the 10 ccm. of the culture of the comma-bacilli, i 

 ccm. of German tincture of opium for every 200 grms. of the 

 animal's body-weight were injected into the peritoneal cavity ; 

 the animal became narcotized for half an hour, and died 

 after one and a half to three days with the same symptoms 

 as the above guinea-pig ; " eighty-five guinea-pigs have been 

 infected in this way with cholera." 



Now the following criticisms can, I think, be justly 

 applied to these experiments : (i) According to Koch's own 

 showing it cannot be the narcosis which is essential, even 

 allowing for the present that relaxation of the intestine may 

 have been produced by the intraperitoneal injection of 

 opium-tincture, since alcohol alone was injected by Koch 

 into the peritoneal cavity, and he says that thereby "we 

 were most successful in making the animals susceptible to 

 the cholera infection." (2) Can narcosis of the animal be 

 produced by opium without furthering in the least the process 

 of the experiment? This has been tried over and over 

 again ; watery extract of opium is injected into the perito- 

 neal cavity, and narcosis lasting for one hour is produced, 

 but the animals remain well ; tincture of opium is sub- 

 cutaneously injected, the animals fall into narcosis lasting 

 for from forty to eighty minutes, but no result is obtained 

 from the previous introduction of the comma-bacilli ; in fact 



