Studies ox Anthrax Infection 



61 



with negative intervals between. A number of other fed guinea 

 pigs are still under observation. The results of these tests would 

 indicate that the intestinal tract is not an easy portal of entry 

 for B anthracis; that healthy susceptible animals can carry 

 virulent anthrax bacilli for a considerable time and by the dis- 

 tribution of the spores in their feces can be a ready means of 

 spread. 



In reading the literature it is evident that the portal of entry 

 is frequently in doubt. In injecting rabbits subcutaneously in the 

 ear we noted that the local reaction was often scarcely notice- 

 able and that the characteristic edema only appeared in the cervi- 

 cal tissues some distance from the portal of entry- and the amount 

 was not always very pronounced. The explanation suggested 

 itself that the firmer tissues of the ear did not allow the edematous 

 fluid to collect at the point where the organism was establishing 

 itself. In the fluid are numerous leucocytes and these may also 

 be prevented from collecting in quantity. Is it not possible there- 

 fore to inject in such tissues a dose of anthrax spores too small 

 to be fatal in the looser tissues but which can establish them- 

 selves where some of the defenses are held in check? To deter- 

 mine this point we took six guinea pigs and injected them with 

 about 50 spores in 1/20 of a cubic centimeter of saline. Three 

 were injected subcutaneously over the abdomen and three under 

 the skin of the ear. The three former lived and two of the latter 

 died, one in forty-seven hours, and one in eighty-four. It is to 

 be noted that the guinea pig dying first had accidently received 

 an extremely small dose. The point of the needle was seen to 

 'be through the ear when the injection was started and the needle 

 was withdrawn at once and so. although undetermined, the 

 amount in the wound must have been minute. The reason the 

 needle was withdrawn was to prevent any undue irritation 

 which would have interfered with the object of the experiment. 

 The autopsy findings in both these animals would not have sug- 

 gested where the injection had been made — a slight amount of 

 edema on the side of the neck in one and a slight amount along 

 the trachea in the other. These are suggestive findings and will 

 need to be repeated many times. 



