TEXT-BOOK OF BACTERIOLOGY. 269 



flow of bile to the intestine undoubtedly favored the success of the 

 experiment. Bile stimulates the muscular movements of the intes- 

 tines, and this fact made it probable that by controlling peristalsis 

 sufficient time is given the micro-organisms to grow and multiply 

 and produce their fatal effects. 



Koch succeeded under these circumstances in effecting success- 

 ful transmission to Guinea-pigs. 



First administer to the animal 5 c.cm. of a 5^ solution of carbon- 

 ate of soda by means of a pharyngeal catheter, in order to neutral- 

 ize the gastric juice and the contents of the stomach. Place a 

 wooden gag perforated in the middle between the pig's jaws, lest 

 the catheter be bitten. Next inject the quantity of soda solution 

 stated above; then inject a moderately large quantity of opium 

 immediately into the abdominal cavity, to paralyze the intestinal 

 movements. Generally 1 gramme of tincture of opium to about 

 every 200 grammes of the body weight is used with a Pravaz 

 syringe. The solution is allowed to flow in slowly. This method 

 is necessary, as opium is not readily absorbed in the pigs stomacli. 

 The animals, however, bear this manipulation with impunity; they 

 become somnolent, lie down on their side, and fall into a deep nar- 

 cosis, from which they waken in about half an hour, shortly to be- 

 come as merry and frolicsome as they were before. 



Soon after the opium injection and while the pig is still in an 

 apathetic state the probe is again introduced and 10 c.cm. of a cholera 

 bouillon culture is injected. This ends the experiment. The ani- 

 mal soon recovers, but very soon begins to show signs of discom- 

 fort, refuses food, is affected by a sort of paralytic weakness of the 

 posterior extremities, and has a superficial and retarded respira- 

 tion; it usually dies after forty -eight hours. 



It has been shown that these sym^Dtoms lack a very essential 

 factor prominent in human cholera, viz., symptoms of intestinal 

 disturbance, and that the Guinea-pigs perish without having vom- 

 ited or without having watery alvine discharges. Here, too, the 

 fact was overlooked that the conditions of animals differ from those 

 of man. Guinea-pigs, for instance, do not vomit, and the absence of 

 diarrhoea is accounted for by the extraordinary size of the csecum 

 of these animals, capable as it is of containing considerable quanti- 

 ties of liquid intestinal contents. 



The post-mortem appearance, however, corresponds exactly to 

 cholera. The smaill intestine is congested and filled with a watery 

 fluid containing a great many cholera bacteria. 



These experiments on animals show the ability of the cholera 

 bacteria to develop pathogenic properties in the animal body and 



