436 MICROBIOLOGY 



strated in the filtrate after passing through a Berkefeld filter. 

 This discovery led to many investigations along this line with 

 infective fluids from animals suffering with the diseases of un- 

 determined etiology. In their investigations Loeffler and 

 Frosch (loc. cit.) made the following determinations regarding 

 the destruction of the virus. 



It was killed (1) by drying for twenty-four hours at sum- 

 mer temperatures (maximum 31 C. at mid-day) ; (2) by 

 heating at 37 C. for twelve hours (the effect of a shorter ex- 

 posure at the same temperature was not tried) ; (3) by heating 

 for half an hour at 70 C. ; and (4) by heating for half an hour 

 at 60 C. In one case, however, an animal inoculated with a 

 large dose of lymph which had been thus heated developed a 

 typical attack of the disease. 



Lymph stored in capillary tubes and kept in an ice chest 

 for fourteen days was always infective. After three weeks it 

 was sometimes inactive, but even after eight or nine weeks 

 many samples proved active when large doses were employed 

 for inoculation. 



Fowl pest. In 1901 Centanni and Savonuzzi 5 investi- 

 gated a disease which occurred among fowls in the province 

 of Ferrara, in Italy, and to which they gave the name fowl- 

 plague (peste aviaria).* The disease had apparently existed 

 for a long time in Italy, and although it closely resembles fowl- 

 cholera, it had been differentiated by Perroncito and others 

 from the latter affection by minor clinical and pathological 

 characters-, and by the absence of the easily recognized fowl- 

 cholera bacteria in the blood. The two diseases appear to have 

 been frequently confounded until Centanni and Savonuzzi 

 showed that the cause of fowl-plague is an ultravisible virus, 

 not arrested when a mixture of blood and saline solution is 

 passed through a Berkefeld filter. 



At a later date a very exhaustive study of the disease was 



3 Centanni and Savonuzzi. La peste aviaria. Referred to by 

 Maggiora and Valenti. 



* This disease has since been reported in Austria, Germany and 

 Belgium. 



