ANNUAL REPORT, 1946-47 69 



the virus from tissues of infected birds. The disease was identified in Berkshire 

 Bristol, Essex, Franklin, Hampden, Hampshire, Middlesex, Plymouth, Suffolk, 

 and Worcester counties. Whenever possible, complete case histories on natural 

 outbreaks are being collected, and that information should be helpful in investi- 

 gating and controlling this disease. 



In 8 flocks, eggs collected during active outbreaks of Newcastle disease were 

 examined for the presence of virus. Among 256 eggs examined, the virus was 

 recovered from 34 eggs received from 4 flocks. 



Preliminary studies reveal that birds recovering from exposure to the New- 

 castle virus will give a positive test with the hemagglutination-inhibition test 

 (H I) in a shorter time than with the serum- virus neutralization test. Hemag- 

 glutination inhibiting bodies have been found in sera of birds as early as five days 

 after artificial infection. The H I test should prove of great value in the early 

 diagnosis and control of the disease. 



A few flocks (approximately 10,000 birds) were vaccinated with a commercially 

 produced, killed vaccine. The vaccine failed to induce a definite immunity. 



A limited number of experiments was conducted to determine whether eggs 

 selected during the active and terminal stages of an outbreak of Newcastle dis- 

 ease would produce infected chicks on hatching or during the first two weeks of 

 the brooding stage. The trials conducted thus far have yielded negative results. 

 This phase of the disease is being investigated further since the virus has been 

 detected in fresh eggs, and field observations have led to the recovery of the virus 

 from two-day-old chicks. 



5. Mastitis Testing Laboratory. At the end of the calendar year 1946, facil- 

 ities for operation of the laboratory were incomplete. Plans were made to set 

 up and test equipment early in 1947. 



WALTHAM FIELD STATION 

 Waltham, Massachusetts 

 Ray M. Koon, In Charge 



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

 to this branch by the Departments of Botany, Entomology, Floriculture, Horti- 

 culture, and Vegetable Gardening. Refer to reports of these Departments for 

 results of investigations conducted at this Station. 



PUBLICATIONS 

 Bulletins 



436 Annual Report for the Fiscal Year Ending June 30, 1947. 70 pp. Sep- 

 tember 1946. 



The main purpose of this report is to provide an opportunity for pre- 

 senting in published form, recent results from experimentation in fields or 

 on projects where progress has not been such as to justify the general and 

 definite conclusions necessary to meet the requirements of bulletin or 

 journal. 



