X, B, 2 Barber: Experiments on Immunization 155 
tion of the virulent dose were 620 grams for animal 6078 and 
650 grams for animal 5983—weights greater than those of any 
control and greater than the average of any series; but that 
of animal 6078 was equalled or exceeded by five animals of 
the same series, and that of 5983 by four animals of its series. 
The change in weight of these animals is shown in the tables 
up to April 14, 1913. Some later weighings are: 
TABLE VIII—Animal No. 6078 
Date. Weight in grams. 
July 11, 1913 690 
October 1, 1913 720 
March 17, 1914 750 
June 9, 1914 680 
After death . : 500 
Animal No. 5983. 
July 11, 19138 710 
October 1, 19138 : 710 
March 17, 1914 740 
June 9, 1914 670 
After death 500 
Both animals showed enlarged inguinal glands during the 
whole period following the virulent dose. The fact that these 
enlargements appeared on both sides, increased at various 
periods, and persisted so long would make it unlikely that they 
were due to the avirulent inoculation alone and that neither 
guinea pig was infected by the virulent dose. In animal 5983 
inguinal abscesses formed and opened at least two years after 
the virulent dose. In both animals the tumor formed at the 
point of inoculation by the last avirulent dose persisted for at 
least ninety days after that dose. This greater reaction to the 
dose may have increased the amount of immunization. The 
amount of this reaction, however, was equalled or exceeded by 
three other animals in each of the series to which animals 6078 
and 5983 belong. The average length of time of survival of 
the three of series 2 exhibiting the greater reaction was three 
hundred thirty-three days, only about twenty-one days above the 
average of the series, and the three of series 3 gave an average 
of only one hundred ninety days, considerably below that of the 
whole number in the series. It is evident, then, that a greater 
reaction to the last immunizing dose was not necessarily followed 
by a greater resistance. 
It is possible that these two animals exhibit only a greater 
natural resistance to infection. One of the nontreated controls 
survived the virulent dose for five hundred twelve days. How- 
ever, the facts that animal 6078 survived this control by three 
