THE BACILLUS OF TYPHOID FEVER. 355 



through a vein in rabbits. The influence of quantity of material 

 used is especially shown in the case of the mice, and the question 

 arises whether the pathogenic power of the bacillus for these animals 

 does not depend upon the simultaneous injection of the ptomaine de- 

 veloped 4n cultures as a result of the vital activity of the organism. 

 Thus we read that mouse No. 4 resisted an injection of a diluted cul- 

 ture, No. 1, but succumbed to a more concentrated suspension one- 

 fifth of a Pravaz syringe. Mouse No. 5 was not killed by the 

 injection of one-third of a syringeful of a diluted culture, but subse- 

 quently died from the injection of one-third of a syringeful of an 

 undiluted culture. Mouse No. 16, injected October 10th with half 

 of a syringeful of a very diluted culture, did not die. The injection 

 was repeated on the 17th of October with half a syringeful of an un- 

 diluted culture, with fatal result. 



In all, thirty-five mice were injected, with a fatal result in twen- 

 ty-seven cases. In rabbits the injections were ' commonly made in 

 the large vein of the ear, and the quantity of material injected was 

 considerably greater from one-third the contents of a hypodermatic 

 syringe to two syringefuls. In some instances death occurred with- 

 in a few hours, in others on the following day or after an interval of 

 two or three days. It is noticeable that the results differ very great- 

 ly as to the date of death and the relative quantity of material re- 

 quired to produce a fatal result. This probably depends to some 

 extent upon the size of the animal, and perhaps partly upon indi- 

 vidual differences in resisting power. 



The experiments, considered together, show that the typhoid ba- 

 cillus is not pathogenic for these animals in the same sense as is the 

 anthrax bacillus or the bacillus of rabbit septica3mia. These organ- 

 isms introduced beneath the skin or into the circulation in the small- 

 est amount infallibly produce death, and at the expiration of a pe- 

 riod of time which is tolerably uniform. 



In all, seventy-nine experiments upon rabbits were made, with the 

 following result : Five injections into the intestine, five into the sub- 

 cutaneous connective tissue, one into the lung, and two inhalation 

 experiments, all without result; twenty injections into the peri- 

 toneal cavity furnished two, and forty-six injections into the vein of 

 the ear twenty positive results i. e. , were fatal to the animal. 



In the fatal cases the bacilli were proved to be present in the 

 spleen by culture experiments and by microscopical examination of 

 properly stained sections. The colonies were identical in appearance 

 with those found in the spleen of cases of typhoid in man. Col- 

 onies were found in the spleens of the rabbits experimented upon 

 exactly as in the human subject sometimes in the trabecuhe, some- 

 times in the Malpighian bodies, sometimes free in the splenic pulp. 



