20 CONTROL SERIES No. 63 



S. pullorum with negative results. This experiment was repeated with 61 chicks 

 in a similar manner with the exception that Group II was brooded by 1 positive- 

 reacting hen. S. pullorum was not isolated from these chicks when killed at two 

 to three weeks of age. In a third experiment, 8 hens were fed infective eggs. 

 Three weeks after feeding the eggs, feces were collected from hens and 5 per cent 

 were mixed with the chick feed and fed to 12 day-old chicks with negative results. 

 Weldin and Weaver (97) were successful in isolating 5. pullorum from feces of 

 infected chicks by bacteriological methods. They also were successful in demon- 

 strating S. pullorum in feces from both artificially and naturally infected chicks 

 when feces from infected chicks were collected in tin or cardboard trays, washed 

 off in water, and the suspension added to the drinking water of non-infected 

 chicks. Non-infected chicks also were infected when feces from infected chicks 

 were transferred to the floor of the pen of non-infected chicks. Dalhng and 

 AUen (20) recovered 5. pullorum from 2 of 3 chicks which died after being placed 

 in a box which had been left untouched for 1 month following the death of 2 

 chicks which had been fed a culture of 5. pullorum. 



In studying the viability of 5. pullorum, Allen and Jacob (1) were able to 

 recover the organism from soil samples for 10 to 14 months after artificial inocu- 

 lation. Kerr (56) reports the recovery of 5. pullorum from fecal emulsions which 

 had been retained for more than three months. The maximum length of time 

 in which he was able to recover the organism was 101 days. 



While the results of these investigations would indicate that pullorum disease 

 may be disseminated through the feces, the relative importance of feces as a ve- 

 hicle of dissemination was not determined. To obtain further information on 

 the importance of feces as a vehicle of dissemination, the following ex-periments 

 were conducted. 



Procedure 



In the first experiment, pullorum disease-free birds were exposed to soil con- 

 taminated with feces from positive-reacting hens. Two groups of non-reacting 

 hens were used. Group I (16 R.I.R. and 4 B.P.R. hens) was purchased from a 

 breeder whose flock has been free from pullorum disease, as determined by the 

 tube agglutination test, for 3 consecutive years. Group II (12 R.I.R. hens) 

 was purchased from a breeder whose flock has been free from pullorum disease, 

 as determined by the tube agglutination test, for 7 years. Both groups of birds 

 were tested when received and were negative to the tube agglutination test. 



The feces were obtained from a group of positive-reacting hens, isolated in 

 an 8 x 12 foot house, and were collected from the dropping boards once a week. 

 The roosts and dropping boards were screened with wire poultry netting. Two 

 grassed plots of ground (8 x 12 feet) adjoining the house of the same size were 

 used. The plots were not shaded but were entirely open to the sun. 



Feces were scattered on Plot I at weekly intervals, beginning April 6, 1931, 

 and continuing until November 17, 1931. The mean average temperatures for 

 the months of April to November, inclusive, procured from the meteorological 

 reports, Massachusetts Agricultural Experiment Station, were as follows: 



Mean Average 

 Month Temperature 

 August 69.6° F. 



September 64.8° 

 October 53.6^ 



November 44.1° 



Approximately one-third bushel of feces from the positive-reacting birds 

 was scattered on Plot I each week for 8 weeks. Group I (20 hens) was then 



