40 CONTROL SERIES No. 63 



in the serum of a chick artificially infected. Later Rettger, Kirkpatrick, and 

 Jones (76} state that while the macroscopic agglutination test was of value in 

 detecting ovarian infection of adults, it had not been of value in detecting the 

 disease in chicks. Doyle (27) reports the detection of 11 reactors in 21 chicks, 

 survivors of a natural outbreak, tested at 2 months of age. May and Segelin 

 (64) state that the agglutination test performed on surviving chicks, about 3 

 weeks after artificial infection, revealed only sporadic reactors. Dearstyne, 

 Kaupp, and Wilfong (23) reported testing and necropsy results on groups of 

 chicks, the progeny of reactors, between the ages of 50 and 90 days. Reactors 

 were found in each group of chicks. Dunlap (28) noted 2 reactors in a group of 

 25 artificially exposed chicks tested at 4 weeks of age. 



General Procedure for the Investigations 



1. Investigations concerning S. pullorum agglutinins in chicks were con- 

 ducted over a period of approximately one and one-half years, and are reported 

 in five parts. 



2. Day-old chicks, except as otherwise described, were obtained from two 

 flocks which had been tested for pullorum disease and had been negative for at 

 least two successive years. 



3. The method of artificial exposure which Weldin and Weaver (97) found 

 most satisfactory was modified by using one strain of S. ptdlorum instead of two. 

 A 24-hour broth culture of a known pathogenic strain of 5. pullorum was used 

 and diluted by adding 45 cc. of physiological saline solution to 5 cc. of the culture. 

 At first a pipette and later a Luer syringe were used for oral administration of 

 0.1 to 0.15 cc. of the diluted culture. 



4. Blood samples obtained before the chicks were 4 weeks of age were 

 collected from the cervical blood vessels when the chicks were destroyed. Other 

 blood samples were collected from an incision of the wing vein. 



5. Tube agglutination tests were incubated 24 hours at 37 ° C. and 24 hours 

 at room temperature (22°-25°C.). Readings were recorded as 4-complete; 

 3-incomplete ; 2-partial; 1-slight; and 0-negative agglutination. 



6. Necropsies were performed on all chicks which died or which were killed. 

 Resultant S. pullorum cultures were subjected to morphological, biochemical, 

 tinctorial, and serological examinations. 



Consignments of chicks from 6 flocks were received at the laboratory for 

 diagnostic purposes. In these consignments there were 15 living chicks, varying 

 in ages from 5 to 19 days. Immediately prior to necropsy, blood samples were 

 collected. Tube agglutination tests were made in dilutions of 1:25, 1:50, and 

 1:100. The re.sults of the tests and bacteriological examinations are shown in 

 the following table. 



■Two chicks negative, one chick partial 1:25, shght 1:.'J0, negativo 1:100. 

 '* The serum of this chiok was negative. 



