ERADICATION OF PULLORUM DISEASE 1931-32 15 



perature. In the routine collection of over 500,000 blood samples during parts 

 of two testing seasons, jellied samples occurred more frequently when the aver- 

 age mean atmospheric temperatures were low. The percentage of jellied samples 

 increased progressively during the months of October, November, and Decem- 

 ber respectively. This increase in the percentage of jellied samples, when the 

 temperature becomes low, may be associated with the inhibitory influence of 

 cold on the clotting of blood. The individual blood collector appears to be 

 another contributing factor in the jellying of samples. It is not apparent how 

 this influence is exerted, but it may be due to slight individualistic differences 

 in the method of collection. 



Conclusions 



1. A jellied condition was produced in chicken blood samples by immediate 

 centrifugalization and by exposure to low temperatures. 



2. The atmospheric temperature at the time of collection appeared to be a 

 major factor in the incidence of jellied blood samples of chickens. 



3. The application of heat materially reduced the number of jellied samples. 



4. The application of heat immediately after collection was found to be 

 more satisfactory for reducing the number of jellied samples than the application 

 of heat at the laboratory 16 to 24 hours later. 



5. The individual blood collector was a variable factor in the incidence of 

 jellied samples. 



6. The incidence of jellied samples was greater among samples containing 

 0.5 cc. of blood than among those containing 1 cc. 



NON-INFECTED FEMALES MAY CONTRACT PULLORUM DISEASE 

 THROUGH EATING FRESH EGGS LAID BY INFECTED HENS 



The problem of eradication of pullorum disease is most difficult since adult 

 birds may harbor in the ovarian tissue the causative organism which can be 

 transmitted to the progeny by means of the egg. The presence of S. pullorum 

 both in fresh and in incubated eggs has been detected by several investigators. 

 Rettger and Stoneburn (72) found the organism in incubated fertile and infertile 

 eggs. Jones (51, 52) isolated 5. pullorum from incubated eggs and later recov- 

 ered the organism from fresh eggs laid by hens that had overcome an acute 

 attack of the disease during chickhood. Rettger (75), in an examination of ap- 

 proximately 10,000 eggs, found that 5. pullorum could be isolated with less 

 difficulty from incubated than from fresh eggs. He advised that in testing for 

 the organism, the entire yolk or a large portion of it be used, or that only eggs 

 which have been incubated for at least five or six days be examined. The organ- 

 ism may even escape detection in eggs that have been retained at ordinary room 

 temperature for two weeks if a large part of the yolk is not examined. Gwatkin 

 (39) found 4.76 per cent among 420 eggs examined infected with S. pullorum. 

 Runnels and Van Roekel (82, 83) reported that 14 per cent of 305 eggs contained 

 5. pullorum. The percentages of isolations were approximately the same for 

 fresh and incubated eggs. In a later experiment, the organism was recovered 

 from 33.7 per cent of 169 eggs examined. Dearstyne, Kaupp, and Wilfong (23) 

 reported that among 2,706 fresh eggs examined, 10.3 per cent contained the 

 organism. Tittsler, Heywang, and Charles (90) found 5.2 per cent of 1,560 

 eggs infected with 5. pullorum. The majority of these eggs were incubated at 

 37° C. for 10 days prior to examination. If this means of dissemination did 

 not exist the malady would not be of such importance, and the task of control 

 and eradication of the disease might be far less difficult. 



