PART 11.— SUMMARY AXT) COXCLL SIGNS. 
The period of incubation of serum anaphylaxis is about seven days 
in guinea pigs sensitized in the brain and about nine days in guinea 
pigs sensitized subcutaneousl}^. It also appears that the sensitization 
comes on somewhat gradually. 
Judged by our results and the work of others, the period of incuba- 
tion is quite constant. 
It seems that the period of incubation is not appreciably prolonged 
by a large sensitizing dose. 
Ajiimals sensitized with horse serum alone remain so for a long 
period of time (at least 245 days). Guinea pigs sensitized with the 
toxine-antitoxin mixture remain sensitive throughout the remainder 
of their life (at least 732 days). 
The sensitizing principle is gradually influenced by heat. It disap- 
pears almost entirely when horse serum is heated to 100° C. for one 
hour. 
Guinea pigs may be sensitized by intracerebral injections, provided 
quantities of 0.000,1 c. c. or more are used. We obtained negative 
results with sensitizing doses of 0.000,01 c. c. into the brain. 
Guinea pigs may be sensitized by dropping horse serum upon the 
eye. 
The toxic principle in horse serum is gradually destroyed by heat. 
A temperature of 70° C. for one horn* does not seem appreciably to 
diminish the poisonous property of horse serum, but it seems to be 
affected at 80° C. for one hour. At 90° C. for one hour it still remains 
slightly toxic, but at 100° C. for one hour the toxicity apparently dis- 
appears. 
The difference in the effect of heat u])on the sensitizing and the 
toxic principle may be more apj^arent than real, for exceedingly min- 
ute amounts of serum will sensitize guinea pigs, wliile it would take a 
very large quantity of weakened serum to produce symptoms at the 
second injection. 
The toxicity of horse serum does not appear to diminish with the’ 
age of the serum. 
Xo favorable influence upon the anaphylactic state was obtained 
by injecting pancreatin, potassium oxalate, pepsin, sodium sulphate, 
magnesium sulphate, peptone, calcium chloride, and calcium acetate 
into guinea pigs the day before they were tested. 
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