102 MASS. EXPERIMENT STATION BULLETIN 388 



Ohio, and Wisconsin. Avian encephalomyelitis was definitely identified in three 

 of the four consignments. 



6. Injectioits Bronchitis Studies. During the past year investigations were 

 undertaken in the control of infectious bronchitis, which is a widespread, highly 

 infectious, communicable respiratory disease of chickens causing serious losses 

 among \oung chicks and lading birds. 



Field investigations were started with the objective of inoculating flocks dur- 

 ing the growing age in the hope of producing an immunity which would be of 

 sufficient duration so that the birds would pass through at least one laying season 

 without contracting the infection. Fourteen flocks, representing approximately 

 40,000 birds, were inoculated during the months of June, July, and August. The 

 inocula were prepared from laboratory birds inoculated with a known infectious 

 bronchitis virus. Preliminary observations re\'eal that birds ranging in age from 

 four weeks to four months can be inoculated without serious objectionable post- 

 inoculation results. However, the inoculation of birds six to ten weeks of age pro- 

 duced the most satisfactory results. Chicks under four weeks of age and laying 

 birds should net be exposed to the infection. 



To date no definite evidence of the disease has appeared among the birds in the 

 inoculated flocks. Later in the season a critical test will be applied to the various 

 flocks to determine their resistance to infectious bronchitis virus. 



Laboratory investigations are in progress to develop a practical and economical 

 method for the production and administration of the virus for flock inoculation. 

 The development of a practical and successful inoculation program to control 

 infectious bronchitis will mean a great economic saving to the Massachusetts 

 poultry industry. 



7. Farm Department Brucellosis Control and Eradication. The laboratory 

 cooperated in this work by testing 639 bovine and 53 swine blood samples, by the 

 standard tube agglutination method. 



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

 lymphoid tumor experimentally transmissible in chickens has been maintained in 

 serial passage during the past year. It has retained its fundamental character- 

 istics and in its later passages has shown no tendency to change its behavior. 

 Apparently the tumor has assumed a fixed pattern for its action in experimental 

 birds. The results of the first thirt> serial passages have been published in an 

 article "A transmissible hmphoid tumor of the chicken" appearing in Cancer 

 Research 1: 384-392, 1941. 



The collection of 384 spontaneous tumors of chickens has been investigated and 

 much interesting information has been the result of this study. The collection 

 was derived from three sources; namely, cases of tumor submitted to the Diagnos- 

 tic Laboratory during a two->'ear period, cases of tumor occurring in a flock from 

 which nearly all birds found ill or dead were examined, and cases of tumor found in 

 birds from other miscellaneous sources. Twenty-three different types of neo- 

 plasia were found in the collection. The most common was lymphocytoma, as 

 slightly over half (55.5 percent) of the cases were of this variety. Six other types 

 (leiomyoma, embrxonal nephroma, myelocytoma, leukosis, epithelioblastoma, 

 and fibrosarcoma) collectively comprised about one-third (32.8 percent) of the 

 collection. Other varieties of neoplasia found were carcinosarcoma, neurogenic 

 sarcoma, hemangioma, fibroma, cholangioma, hepatoma, histiocytic sarcoma, 

 my.xoma, thymoma, rhabdomyoma, osteochondrosarcoma, fibrochondrosarcoma, 

 melanoma, lymphangioma, mesothelioma, and teratoma. 



Three forms of lymphocytoma were found: diffuse, nodular, and combined 

 diffuse and nodular. A possible explanation for the existence of three forms was 



