106 MASS. EXPERIMENT STATION BULLETIN 378 



6. Viability of S. pullorum.. Studies to determine how long S. puUorum 

 will remain alive in a dry piece of cloth stored at room temperature 

 showed the organism to be alive after 7 years, 8 months, and 4 days. 

 The last of the cloth prepared for this investigation was examined at the 

 end of a period of 8 years, 3 months, and 8 days and no viable organisms 

 M^ere recovered. 



7. Transmission of Pullorum Disease by Cohabitation. An attempt to 

 transmit pullorum disease to non-reacting females gave negative results 

 when non-reacting females and reacting males were confined in the 

 same pen over a period of 9 months. 



8. Avian Encephalomyelitis. Investigations during the past year have 

 further substantiated that mature pheasants appear refractory to the in- 

 fective agent when inoculated intracerebrally. Pheasant chicks inocu- 

 lated intracerebrally failed to show definite symptom.s, but brain suspen- 

 sions prepared from these pheasants 76 days after the inoculation re- 

 vealed that the infective agent was still present and capable of producing 

 the disease in chicks. The virus was not demonstrable in the spleen after 

 this period. Cohabitation of inoculated chicks with susceptible chicks 

 produced positive transmission to the latter. The degree of spread how- 

 ever was slight. Fresh citrated blood obtained from affected chicks was 

 capable of producing the disease in chicks when inoculated intracerebrally, 

 intraperitoneally, and subcutaneously. This was likewise true of liver and 

 spleen tissues inoculated by the intracerebral route. Chicks inoculated 

 by intraperitoneal and subcutaneous routes readily contracted the disease. 

 A group of 309 chicks (consisting of 2 different hatches) were hatched 

 from eggs obtained from a commercial breeding flock whose progeny re- 

 vealed one outbreak of the disease. The chicks were hatched and reared 

 under control conditions. No evidence of the disease was noted. The 

 infective agent used in some of the above-mentioned experiments is now 

 in its 104th serial passage. Through repeated passage in chicks, the virus 

 acquired a shorter incubation period, a shorter disease course, and a mor- 

 tality rate of 100 percent. 



9. Farm Department Brucellosis Control and Eradication. The laboratory 

 cooperated in this work by testing 328 bovine blood samples with the 

 standard tube agglutination method. 



Studies of Neoplastic and Neoplastic-like Diseases. (Carl Olson, Jr.) 

 The transmissible lymphoid tumor of the chicken (described previously 

 in Annual Reports for Years Ending November 30, 1938 and 1939) has 

 now been carried through more than 60 serial passages in experimental 

 chickens. The results for the first 30 passages in whch birds received 

 implants of the tumor either in subcutaneous or muscular tissue are 

 summarized in the following table: 



Regression of the growth occurred in 133 of the 300 chickens after it 

 had reached a maximum state of development on an average of 13.6 days 

 after inoculation. No pertinent pathology was observed in these birds at 

 necropsy. The tumor had remained localized and actively growing in 

 116 of the chickens at the end of their experimental life, which averaged 



