98 DISEASES OF DOMESTICATED BIRDS 
Tenacity of virus. Burnet observes that finely powdered. virus 
in physiological salt solution placed in sealed ampoules in a water 
bath at 60° C. is killed in about 8 minutes. At 56° C. the finely 
powdered virus does not resist longer than half an hour. In sus- 
pension in water at 37° C. it has been found inactive after 8 days; 
active after 3 days; active after 30 days at 22° C.; active after 6 
days at 25° C. Marx and Sticker found virus active after 3 hours 
at 60° C., but the material probably was not as finely powdered as 
in the experiment conducted by Burnett. The same authors found 
that desiccated virus in ampoules deprived of air remained active 
after an hour at 100° C. Scabs exposed to the sunlight in a Petri 
dish were still virulent after two months. Reischauer observes that 
the virus resists dry heat at 80° C. for 15 to 80 minutes and moist 
heat 5 minutes at 100° C. Marx and Sticker found a suspension of 
crusts virulent after 114 hours in a 1 per cent solution of carbolic 
acid. In solutions of 2 and 21% per cent it lost its virulence. 
Reischauer notes that the virus is killed in 5 minutes by 1 per cent 
solution of potash, acetic acid or carbolic acid. Burnett kept, a sus- 
pension of virus in ordinary water in a refrigerator at 6° OC. for 60 
days and found it virulent after that length of time. Finely pow- 
dered virus mixed with glycerine was found to be virulent after 120 
days. 
Haring and Kofoid tested the effect of various germicides upon 
powdered pox virus. The virus was saturated with the germicide 
and after the lapse of a certain amount of time, the virus was in- 
oculated into a fowl by scarification. Five per cent carbolic acid 
failed to kill in 20 minutes; 2 per cent liquor cresolis compositus 
failed to kill in 20 mines 2 per cent potassium permanganate 
failed to kill in 20 minutes; 2 per cent copper sulphate failed to kill 
in 20 minutes; tincture of iodine failed to kill in 10 minutes; mer- 
curic chloride in 1: 1000 solution failed to kill in 20 minutes; steam 
heat at 100° C. failed to kill the virus in 5 minutes but did do so in 
30 minutes; dry heat at 200° C. killed the virus in 30 minutes. 
Powdered pox scabs saturated with physiologic salt solution and al- 
lowed to decompose for 10 days in a warm place proved non-virulent. 
Dry powdered pox scabs kept in a test ae from May, 1906, to Sep- 
tember, 1911, proved virulent. 
Pathogenicity. Diphtheria and pox are especially prevalent 
in chickens and pigeons, and are also common in turkeys, geese, 
ducks and guinea-fowl. Pheasants, quail and various wild birds are 
susceptible. 
