BACILLARY WHITE DIARRHEA Te 
teriological examination of eggs from a suspected flock also leads to 
a diagnosis. However, this method is impractical because of the 
fact that an infected hen only occasionally drops an infected egg and 
considerable laboratory work is necessary to establish the presence of 
the disease. or the detection of individual carriers among hens 
held for breeders, two other methods which give positive proof of the 
presence of infection in the flock and pick out the infected individuals 
with a high degree of accuracy have been developed. These are the 
agglutination test applied first by Jones, and the intradermal test 
developed by the authors. 
Agglutination test. This test is based on the fact that the blood 
serum of an animal. which has experienced the attack of a given 
species of bacteria will in some instances cause the organisms to 
agglutinate or form into clumps when a suspension of the bacteria 
is mixed with the serum of the animal in proper dilution. 
The wing vein is severed at the point where it passes over the 
elbow joint and 8 to 5 ac. of blood collected in a sterile test-tube or 
vial. The flow of blood is then stopped by momentary pressure over 
the cut, or by the application of a small pledget of cotton. Usually 
no effort is necessary to stop the flow of blood, as chicken blood clots 
readily. Blood may be drawn more rapidly by severing the promi- 
nent vein visible on the ventral surface of the wing near the shoul- 
der. The collected sample is set aside and allowed to clot. It 
should not be agitated while the clot is forming, as this tends to 
prevent the collection of a clear serum. After the clot has formed, 
the sample may be placed in a refrigerator or other cool place. In 
a few hours the serum will have been pressed out by the contraction 
of the fibrin and can be drawn off as a clear fluid, free of blood cor- , 
puscles or hemoglobin. If the test is not to be made immediately, 
the serum may be preserved by the addition of carbolic acid in suf- 
ficient quantity to form a .5 per cent solution. For this purpose, 
it is convenient to use a 5 per cent solution of carbolic acid as a 
standard, .1 ¢.c. being added to .9 ¢.c. of serum, or 1 drop to 9 drops. 
For the test a standardized suspension of B. pullorum is prepared. 
This may be heated at 60° C. for one hour, to kill the organisms, or 
used in the live state. The latter has been the practice of the au- 
thors. However, there appears to be no marked advantage in the 
use of live antigen, and killing by heat or .5 per cent carbolization 
has the advantage that the organisms are dead and hence absolutely 
harmless. 
In the test, the bacterial suspension is placed in the test tubes 
