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persons were also treated with the same amount of the vaccine. ‘This 
method of procedure was adopted in order to minimize the danger of 
inoculating a very susceptible individual with a dose which might prove 
disastrous. It was argued that if ten persons selected at random with- 
stood the inoculation of a certain amount of the organism without 
developing unfavorable symptoms, a single individual, also selected at 
random, could probably receive a slightly larger dose without great 
danger. In this manner as mentioned the dose was gradually increased 
until one whole agar slant was inoculated. No attempt has been made 
to inject a larger amount of the organism, since from experiments per- 
formed on animals it has been concluded that a sufficient immunity in 
man will probably result from an inoculation of this quantity. Up to 
the present time forty-two persons have been injected with this large dose 
(one twenty-four hour agar slant culture) of the living bacillus, and, 
although the inoculations which I include in this report were all per- 
formed more than two months ago and the individuals treated have been 
under constant surveillance, I have no accident to report. 
Surprising as it may seem, the injection of these large amounts of the 
living plague organism have not given rise to any very severe reactions. 
A few hours after the inoculation, the temperature of the individual 
usually begins to rise. When the injection has been given in the morning 
the fever may, on the evening of the first day, reach 38.9° to 39.4° C, 
(102° to 103° F.), but rarely has it touched 40° C. (104° F.). On the 
following day, in none of the cases was the temperature above 38.9° C, 
(102° F.) and usually not above 37.8° C. or 38.3° C. (100° or 101° F.) 
and on the third one it generally was normal. Occasionally the cases 
showed a moderate leucocytosis after the large injections. The organisms 
were always suspended in 1 cubic centimeter of .085 saline solution and 
the inoculations were made deeply into the deltoid muscle. On the day 
after the vaccination there usually was distinct induration about the point 
of injection, with some soreness on pressure, but these symptoms subsided 
in one or two days. No suppuration ever occurred. A careful study of 
the blood serum has been made in twenty-nine of the human cases; ag- 
glutintative tests have been performed with the virulent plague organism 
and the anti-infectious power of the serum has been tested in rats. A 
detailed report of all the experimental work will appear in a future 
number of this JouRNAL. 
It was interesting to observe the length of time during which these 
avirulent pest organisms remained alive in monkeys after subcutaneous 
inoculation, and for this purpose a series of ten animals was injected 
upon different days, the cultures being taken at periods of from one to 
twenty-four hours after the inoculation. The abdomen of the animal 
was first shaved, and the injection made subcutaneously. The skin was 
then carefully massaged until apparently the fluid was completely ab- 
sorbed. At the time the culture was to be taken, the skin of the abdomen 
