ANNUAL REPORT, 1942 59 



observed. -Chicks hatched from eggs laid by laboratory breeding stock revealed 

 evidence of avian encephalomyelitis at hatching time. This observation further 

 substantiates previous findings at this laboratory that this infection may be 

 egg-borne. 



6. Infectious Bronchitis. During the past year investigations in the control 

 of infectious bronchitis were continued with the cooperation of the Extension 

 Service and the Massachusetts Division of Livestock Disease Control. The 14 

 flocks inoculated with a laboratory strain of live infectious bronchitis virus in 

 the summer of 1941 passed through the laying season without contracting the 

 disease. In two instances evidence of respiratory infection was observed, but 

 infectious bronchitis was not definitely diagnosed. 



The results of these field investigations were received with great enthusiasm 

 by other flock owners whose flocks had experienced this disease. During 1942 

 the program was extended to additional flocks, in which the infection had previ- 

 ously been observed. Susceptible birds were inoculated or exposed to infection 

 before reaching sexual maturity. In most instances post-inoculation reactions 

 were favorable. However, it was noted that concomitant infections or diseases 

 and climatic and management factors play a definite role in the response of the 

 flock to infectious bronchitis virus. Mature birds which were regarded as im- 

 mune to the infection due to previous exposure failed in every instance to con- 

 tract the disease from the inoculated young stock. The results of the field trials 

 appear encouraging, but before a practical control program is inaugurated fur- 

 ther critical tests should be conducted. 



Investigations have also been continued to develop a reliable method of de- 

 tecting birds that ha\'e been exposed to infectious bronchitis infection. Such a 

 method will serve as a guide in using this virus only in flocks that have had the 

 disease. 



7. Farm Department Brucellosis Control and Eradication. The laboratory 

 cooperated in this work by testing 639 bovine blood samples by the standard tube 

 agglutination method. 



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

 ress under this study was interrupted by Dr. Olson's enlistment in military 

 service and therefore no conclusive report is possible at this time. 



WALTHAM FIELD STATION 

 Waltham, Massachusetts 

 Ray M. Koon, in Charge 



The members of the research staff of the Waltham Field Station are assigned 

 to the unit by the Departments of Botany, Entomology, Floriculture, Horti- 

 culture, and Vegetable Gardening. Reports of these departments give results 

 of investigations conducted at this station. 



Soil Testing Service. Testing soil for commercial vegetable growers, mush- 

 room growers, florists, nurserymen, greenkeepers, arborists, vendors of loam, and 

 home gardeners has long been regarded as an important service which the Field 

 Station has rendered. More recently this program has been extended to include 

 service to the State Department of Public Works, the Metropolitan District 

 Commission, Works Project Administration, U. S. Army Engineers, and town 

 and city administrations. There is no doubt that this effort is effective, partic- 

 ularly when the soil test is followed by a personal interview between the client 

 and the technician. The total number of soil samples tested in 1942 was 6134. 



