18 MASS. EXPERIMENT STATION BULLETIN 323 



The results show that no reactors appeared after all the birds had been subjected 

 to four tests with the whole blood method, although the birds tested on January 

 28 (fourth test) were also tested with the standard tube method which detected 

 six additional reactors, two of which proved to be infected. The results obtained 

 in Flock B are of very great interest in that delayed reacting birds are of signi- 

 ficance in eradicating the disease from a flock. Some birds exhibited delayed 

 reactions consistently or intermittently on subsequent tests, whereas others 

 became either distinctly negative or positive. Delayed reactions were exhibited 

 bv 15 birds during the testing of this flock: two (99017 and 99100) were later 

 detectetLas .positive. reactors, whereas the remaining 13 became negative to the 

 whole blood test. Of this latter group one (99039) was later detected with the 

 tube test and found infected on necropsy. (S. pullorum was isolated from peri- 

 cardial fluid, liver, spleen, peritoneum, ovary, and abdominal cyst). Bird 99181 

 was also detected on the fourth test with the tube method but did not react with 

 the whole blood test. This bird gave a doubtful reaction with the whole blood 

 method at a later date and at necropsy S. pullorum was isolated from the peri- 

 cardial fluid, liver, spleen, peritoneum and ovary. Among the 22 reactors examined 

 at the laboratory, 5. pullorum was recovered from 19. Bacteriological examina- 

 tion of two of the delayed reacting birds revealed that 5. pullorum was isolated 

 from the ovary and abdominal cyst in one (99017), and from the pericardium, 

 liver, peritoneum, ovary, and abdominal cyst in the other (99100). A great fluc- 

 tuation in the degree of reaction with the whole blood test was observed in some 

 birds that were tested at short intervals. Infrequently this fluctuation could be 

 correlated with the variation in serum titre. One bird (99272), reacting to the 

 whole blood test only when submitted to the laboratory, did not react to either 

 method on subsequent tests, and 5. pullorum was not isolated. Two birds reacting 

 only to the tube test did not reveal the organism on bacteriological examination. 



Flock C. This flock had not revealed reactors for two consecutive years. How- 

 ever, on initial test with the standard tube method 17 reactors were detected 

 among 445 birds tested. This flock appeared satisfactory for the purpose of 

 comparative testing with the whole blood and standard tube methods. Upon 

 recognition of infection in the flock, the owner was requested not to dispose of 

 reactors until after the first comparative test. 



On October 24 and 25, 1934, the entire flock was tested with the whole blood 

 test and standard tube method, using the testing apparatus with the improvised 

 water heating system. A total of 1053 birds was tested and revealed 40 reactors — 



19 with the tube method, 2 with the whole blood test, and 19 with both methods. 

 The reactors were treated in the following manner: — 



Slaughter Quarantine Laboratory Total 



Birds reacting to tube test only .. . 16 3 19 



Birds reacting to W. B. T. only. . . 2 2 



Birds reacting to both methods ... 10 4 5 19 



Total 10 20 10 40 



On November 28, 1934, a total of 732 birds was tested with both methods and 

 only three birds gave a doubtful reaction with the tube method. These birds 

 (95825, 95829 and 96027) were submitted to the laboratory for further study. 

 A part of the flock, representing old hens which had been non-reacting for two 

 seasons, was not tested. Among the 20 reacting birds held in quarantine, 18 

 survived the second test and revealed three reactors (one with both methods 



