EXPERIMENTAL INOCULATION 369 



maintain the virulence after exaltation the organism should be grown on a broth 

 which before sterilization turns phenol- phthalein pink and to which a few 

 drops of guinea-pig blood have been added just before sowing it (Rodet and 

 Lagriffoul). 



(b) ChaDtemesse and Widal also raised the virulence of bacilli moderately 

 virulent [for experimental animals] by passage through guinea-pigs, utilizing 

 to that end a discovery of Vincent relative to the exaltation of the typhoid 

 bacillus when associated with sterile cultures of streptococcus pyogenes. 

 They inoculated into the cellular tissues of a guinea-pig 4 c.c. of a culture 

 of a typhoid bacillus and at the same time into the peritoneal cavity 8-10 c.c. 

 of a culture of a pyogenic streptococcus which had been sterilized at 100 C. 

 for 1 hour. The animal died in less than 24 hours and the typhoid bacillus 

 was found to have become generalized. The organism was passed through a 

 series of guinea-pigs and the dose of sterilized streptococcus emulsion gradu- 

 ally diminished, with the result that the typhoid bacillus soon became so 

 virulent that a few drops introduced into the peritoneal cavity caused the 

 death of the animal. 



(c) According to Chantemesse and Balthazard the most efficient method of 

 raising the virulence of a typhoid bacillus to a maximum is to sow a culture 

 in a collodion sac, and after leaving it in the peritoneal cavity of a guinea- 

 pig for 24-36 hours to sow the Contents in broth : the growth is very abundant 

 so that in 12 hours the surface is covered with a thick pellicle. This culture 

 is fully virulent. 



Infection with viruses of exalted virulence. Guinea-pigs are the best 

 animals for the study of typhoid infections. A few drops of an exalted virus 

 inoculated into the peritoneal cavity gives rise to a typical attack of the 

 disease. 



Two to four hours after inoculation the temperature rises and may reach 

 41 C. but it soon (6-12 hours) begins to fall to 36 C. and perhaps 32 C. ; 

 synchronously with the fall of temperature collapse sets in and the animal 

 dies 15-30 hours after the inoculation. 



During the febrile period the animal is dull and refuses its food. When 

 the temperature has become subnormal it huddles itself up in a corner of its 

 cage, the abdomen is painful and the animal rapidly wastes. 



Post mortem examination. The peritoneal cavity is found to contain a 

 variable amount of an opalescent serous fluid very rich in bacilli (the greater 

 the virulence of the organism the less the effusion) : the spleen, liver, kidneys, 

 intestines and notably the Peyer's patches are swollen and congested : the 

 mesenteric glands are swollen and in some cases there is a little pleural effu- 

 sion : the -intestine contains a serous fluid rich in bacilli. According to 

 Chantemesse and Widal these latter are typhoid bacilli but according to 

 Sanarelli they are very virulent colon bacilli. 



The organism is found in pure culture in the peritoneal exudate and also 

 in the internal organs, blood etc. 



C. Infection by the alimentary canal. 1. Monkeys. Chantemesse and 

 Ramond fed a Macacus rhesus for a fortnight on an exclusively milk diet 

 and then gave it a virulent agar culture of the typhoid bacillus mixed with 

 jam. As early as the third day the animal experienced a rise of temperature, 

 anorexia and diarrhoea, and was dead at the end of a week. Post mortem 

 examination revealed lesions characteristic of human enteric fever especially 

 in the neighbourhood of Peyer's patches. 



2. Rabbits. Kemlinger succeeded in infecting rabbits by starving them for 

 2 or 3 days and then feeding them for 5-10 days on vegetables contaminated 

 with cultures of the typhoid bacillus. Many of the animals remained 



2A 



