26 N. H. Agr. Experiment Station [Bulletin 262 



nearly 600 chicks each were entirely lost due to the transmission of the 

 disease from parent stock to progeny. The lowest mortality of the 

 next three hatches was 93 per cent. The incubator was treated with 

 formaldehyde gas and the mortality of the following hatch dropped to 

 37 per cent. 



The parent flock was then tested and 120 reactors removed. The 

 mortality of the next hatch up to three weeks — the period on which all 

 the mortality figures in this research are based — had dropped to 15 

 per cent. Testing had begun in March. By October the flock was en- 

 tirely free from the disease, a total of 156 reactors having been re- 

 moved from the original 500 birds. 



The young stock produced from this flock was also under test, be- 

 ginning at approximately three months of age. Nearly 200 of the flock 

 of 700 were eliminated as reactors. The 800 progeny of this second 

 generation were tested at the age of seven months and found 100 per 

 cent, free from the disease. 



A second adult flock of nearly 1,000 was divided into five groups 

 of hens, young cockerels, and pullets hatched at various periods the 

 preceding spring. These were tested monthly for about eight months 

 and more than 650 reactors removed. About six months later another 

 series of four monthly tests was made and complete freedom from pull- 

 orum disease definitely established. (Purnell Fund) 



Study of Paralysis of Poultry 



Paralysis of poultry is being investigated by C. L. Martin and 

 A. E. Tepper through a study of the blood and bones of mature birds. 

 The work the past year was confined to blood counting. Chemical 

 analyses will be repeated. Then the birds will be killed and a sectional 

 study made of their intestines, liver and pancreas. (Purnell Fund) 



Vaccinating for Fowl-Pox 



Skin vaccination for the prevention of fowl-pox with a non-at- 

 tenuated virus, was continued throughout the year by C. L. Martin and 

 C. A. Bottorff. The improved "stab" method was used successfully 

 for the second consecutive year. To determine the best storage for 

 fowl-pox virus so that its virulency may be maintained, it was stored in 

 the form of ground and unground scabs in air-tight containers at ice- 

 box and at room temperatures. It is tested monthly. (Purnell Fund) 



Testing for Contagious Abortion 



Efforts to control contagious abortion in cattle through the use 

 of the agglutination test have shown the same good results as in the 

 past, reports C. L. Martin. Herds rid of positive reactors have re- 

 mained free from the disease as evidenced by negative tests. Other 

 herds with the reactors segregated in the same stable have gradually 

 been able to replace the infected animals with non-infected home-raised 

 heifers. It is expected that by following this practice a clean herd 

 will result in due time, and apparently at very little expense to the 

 dairyman. 



Veterinarians submitted 3,345 samples to our pathological labora- 



