76 MASS. EXPERIMENT STATION BULLETIN 327 



laboratory. The chicks were two to five weeks of age when received, the first 

 symptoms being noted between the nintn and twenty-first days. Morbidity 

 in the affected flocks varied up to almost 50 percent and mortality possibly 

 up to 20 percent. After a period of approximately eight months, 24 chickens 

 of the original 83 survived. The losses in this group from "epidemic tremors" 

 were supplemented by losses from intercurrent diseases and by specimens 

 sacrificed for experimental purposes. Blindness, a previously unreported 

 symptom of "epidemic tremors," has been observed, following an opacity and 

 bluish discoloration of the lens of one or both eyes. Seven of the 24 living birds 

 show this condition. Progeny of the 24 survivors are under observation. A few 

 of the progeny have exhibited a very fine muscular tremor at about five weeks 

 of age, which was not observed in normal birds. Typical tremor and ataxia 

 encountered in natural outbreaks of the disease were not observed in the 

 progeny. In five trials 62 chicks from 2 to 24 days of age were inoculated 

 intracerebrally with brain emulsions from affected chicks, and gross mani- 

 festations of disease were not observed. 



6. Disease Studies in Wild Animals. Our knowledge concerning the influence 

 of disease on the conservation of wild life is very meager at the present time. 

 During the past year specimens (normal and morbid ) have been investigated 

 from anatomical and pathological points of view. Disease entities which were 

 bacterial, fungous, protozoan, or parasitic in character, have been encountered 

 in the various specimens. Most of the specimens examined were ruffed grouse 

 which were reared in captivity by the Poultry Department. The majority 

 apparently died from inanition when less than a week old. Renal disorders 

 were rare, and perosis, noted frequently the preceding year, was not observed. 

 Among a group of eight growing birds, ulcerative enteritis appeared during the 

 month of August. All birds succumbed to this disease within a week. Through 

 effective managerial and sanitary methods, ulcerative enteritis was prevented 

 in birds that were maintained on wire. However, one case of entero-hepatitis 

 was encountered in this group. 



7. Farm and Station Bang Disease. In assisting this project, the laboratory 

 tested 1,565 blood samples by the standard tube agglutination method. 



Laryngotracheitis. (C. S. Gibbs. ) Three outbreaks ol laryngotracheitis 

 in brooder chicks have been studied in which the viruses were of low virulence 

 and produced clinical symptoms resembling colds. The virulence was not 

 enhanced after passing serially through 36 chicks. These viruses neutralized 

 two known laboratory strains of laryngotracheitis, and chicks immune to the 

 field virus were immune to the laboratory virus and vice versa. 



Colds. (C. S. Gibbs. ) Two types of colds have been studied, one in which 

 the symptoms and lesions are confined to the nostrils, infraorbital sinuses and 

 turbinates, and the other in which the trachea and bronchi are involved. Both 

 types are apparently due to the same virus, because they are readily trans- 

 mitted to the nostrils, infraorbital sinuses and turbinates or to the trachea, 

 depending upon the method and site of inoculation. Moreover, chickens made 

 immune to one type of cold are immune to the other also. Chickens immune 

 to these colds were not immune to laryngotracheitis, and chickens immune to 

 laryngotracheitis were not immune to these colds. 



Studies thus far seem to indicate that colds in chickens or laying hens are 

 not serious unless they are complicated by secondary microorganisms. The 

 most common complications appear to be Staphylococcus albus, Streptococcus 

 bronchitis, and Hemophilus gallinarum. These microorganisms produce pus 



