April, 1931] Agricultural Research in N. H., 1930 23 



months the infection in the clean group was increased to three per cent. 

 Two months later this had reached four per cent. 



An even greater spread was observed in the infected group, which 

 showed a nine-per-cent infection at the beginning of the experiment. 

 One month later this infection spread to 20 per cent of the group. The 

 next one and one-half months resulted in a gain of only three per cent, 

 with no additional spread two months later. (Purnell Fund) 



New Way to Vaccinate for Fowl Pox 



A new way of vaccinating poultry to prevent fowl pox has been test- 

 ed on New Hampshire farms during the last two years by C. L. Mar- 

 tin and C. A. Bottorff and found superior to the older "follicle" pro- 

 cedure. Known as the Johnson stick method, it is reported quicker 

 and easier, more economical on vaccine, equally efficient, and the cause 

 of fewer head lesions. 



Further investigations were made with the assistance of A. E. Tep- 

 per as to the length of incision necessary for a good "take" and the 

 best type of vehicle to carry vaccine. As to the latter no difference 

 was found in a combination of sterile glycerine and distilled water, and 

 distilled water alone. Three types of incisions were tried — a stab, 

 one-eighth inch incision, and one-fourth inch incision — and all proved 

 equally good. (Purnell) 



Poultrymen representing 28 flocks in New Hampshire received 40,- 

 250 doses of fowl-pox vaccine. Most of these men were located in the 

 southern end of the state. The vaccine was also distributed under 

 federal permit to poultrymen in other states, as follows: Massachu- 

 setts, 26,400 doses; New Jersey 10,075; Pennsylvania, 2,200; New 

 York, 1,500; Rhode Island 756; Maine 300; Vermont 50. {Miscella- 

 neous Income) 



Contagious Abortion 



In a study of the control and eradication of contagious abortion of 

 cattle by means of the standard agglutination test, blood samples have 

 been collected at frequent intervals from seven experimental herds near 

 Durham. The work has shown that this disease can be handled by the 

 blood test, coupled with a practical plan of sanitation and isolation of 

 each of the groups of negative, positive, and suspicious reactors. C. L. 

 Martin is in charge. 



Herd No. 1 has remained clean since the last reactors were sold in 

 1926. Herd No. 2 has remained clean since reactors were removed in 

 1928. Herd No. 3 has had one suspicious reactor since the last was 

 removed in 1928. Two reactors were brought back to herd No. 4 which 

 had been isolated and they started abortions in the others, increasing 

 the number of reactors from none to six positive and six suspicious out 

 of 32 head in a period of six months. 



Herd No. 5 was divided into positive and negative groups in the 

 same stable but pastured in different pastures. By observing good san- 

 itation and replacing reactors with non-reacting heifers, the herd has 

 changed since 1929 from eight positive, nine suspicious, and six nega- 

 tive to four positive, four suspicious, and 18 negative. No division was 



