10 BULLETIX 517^ U. S. DEPAKTMEXT OF AGRICULTURE. 
The disadvantages of work with artificially infected birds, due tc 
the large amounts of culture injected and to the severe reactions re- 
sulting, were thoroughly realized, and work with naturally infected 
birds was undertaken. 
FIELD TRIALS OF THE INTRADERMAL TEST. 
Through the courtesy of the Connecticut agricultural experiment 
station, opportunity was afforded to apply the intradermal test to 
two flocks tested at the same time by Dr. L. F. Eettger b}^ the agglu- 
tination method. 
One flock of 231 birds injected on February 28, 1916, contained at 
the time over 10 birds shoAving more or less evidence of swelling of 
the wattles due to frostbite, while 6 others showed very slight swell- 
ino- attributed to the same cause. When examined 33 hours after 
injection none was regarded as showing reaction to the intradermal 
test. One bird gave a reaction to the agglutination test and was 
killed by the owner before arrangements were made to retest by the 
intradermal method. However, the owner had made an autopsy and 
reported that he regarded the bird as infected. 
In the second flock in which work was done the Connecticut Agri- 
cultural Experiment Station tested 50 birds in the regular routine 
Avork of testing. Of these 1 reacted to the agglutination test and 
failed to react to the intradermal test when examined 46 hours after 
injection. A number of birds showed slight abnormal conditions, 
regarded at the time as due to frostbite, but noted in connection with 
the problem of determining the least amount of swelling to be re- 
garded as a significant intradermal reaction, under the conditions in 
question. 
The bird that gave a positive reaction to the agglutination test was 
retested by both methods about a month later by Dr. Rettger. At 21 
hours after injection the wattle was swollen to about 2.5 times normal 
thickness, and when observed at IB hours the swelling was 1.5 times 
normal. An agglutination test made at the same time also gave posi- 
tive results. It is probable that the failure of the intradermal test 
when used the first time was due to some error in technique. Further, 
it is the belief of the writers that readings should be taken at about 
24 hours, and not as late as 36 and 48 hours, as in these trials. 
In the same flock the intradermal test alone vcas applied to about 
100 birds, and those showing any enlargement of the wattle at 46 
hours were tested by the agglutination method by Dr. Rettger. The 
results yielded by both methods are given in Table VIII. The size 
of the swelling following the intradermal injection is indicated as 
nearly as possible by arranging them in order of decreasing size from 
the top to the bottom of the list. Here, again, cognizance was taken 
