18 
tinating. The sera of the white rat, white mouse, and guinea pig 
were negative. 
Laveran and Mesnil state that the normal sera of the chicken and 
horse caused complete agglutination. The sera of the sheep, dog, 
and rabbit produced a partial reaction, while the pigeon, frog, guinea 
pig, white and spotted rats, and sewer rats caused none whatever. 
They also state that, although the blood of chicken and horse have 
agglutinating power, they do not protect against infection. 
3. In the ice chest . — If trypanosome blood is drawn from the rat 
under aseptic conditions and sealed in jDipettes and placed in the ice 
box, the parasites will usually join into beautiful rosettes after 
twenty-four hours. We found them agglutinated in blood which had 
been eighty-three days in the ice chest. 
I 
TRANSMISSION OF THE DISEASE. 
1. By intraperitoneal inoculation . — Although white and spotted rats 
have never yet been found to harbor trypanosomes spontaneously in i 
their blood, we find in them a very susceptible host for experimental 'j 
inoculations, and it was with them that most of our work was done. 
Comparative studies show that a heavy blood infection is obtained bj^ > 
intraperitoneal injection sooner than by any other form of inocula- 
tion. The blood to be injected is mixed with 1 c. c. of saline solution : 
or bouillon and injected with a hypodermic syringe. The period 
which elapses between the intraperitoneal inoculation and the first '\ 
appearance of the parasites in the blood is variable, depending upon 
the amount of trypanosomes injected and the stage of develpment of i 
the injected parasites. 
Rabinowitsch and Kempner place the time at three to seven days, 
although they observed parasites in a few instances within the fii’st : 
day. 
Laveran and Mesnil give three to seven days as the average time ' 
before the blood infection. They found a few in the circulation after i 
five or six hours. 
Jourgens found that the first x>resence of parasites in the tail blood 
occurred three or four days after inoculation, seldom later. After i 
inoculation with 1 c. c. of blood he found them in tail blood in several 
instances after twenty minutes. 
The parasites apiDeared in the tail blood in our cases usually on the ' 
second da3^ This was chiefiy because we injected as a rule larger ' 
doses and used heavilj^ infected blood in which were many develop- ^ 
mental forms. 
There has been considerable discussion as to where the principal 
seat of multiplication takes place in intraperitoneal inoculation. 
Rabinowitsch and Kempner regard the peritoneal fiuid as a better i 
nutritive medium for the development of the parasites than the blood ‘ 
and think that the chief seat of development and multiplication is in 
the peritoneum. In one to- five days after intraperitoneal injection I 
