xii.] Fowl-cholera. 141 



We do not at all know the origin or cause of this difference, and 

 the instance cannot therefore help us to an actual explanation 

 of the phenomenon before us ; it only shows that we are not 

 dealing with a peculiarity confined to Bacteria or to a single 

 Bacterium, but with a special case of a not uncommon series of 

 phenomena. 



Fowl-cholera or fowl-plague (57) is the name given to 

 a disease which attacks domestic poultry, and which shows 

 a similar behaviour to that of anthrax in the points with which 

 we are at present concerned. We learn from Pasteur's researches 

 that it occurs in fowls in an acute and in a chronic form. 

 Characteristic symptoms of the former are a state of profound 

 torpor or stupefaction ; the bird sits with closed eyes and staring 

 feathers perfectly still and taking no notice of anything about it ; 

 this is followed by diarrhoea produced by inflammation and ulcer- 

 ation of the intestinal canal. Dissection also discloses abscesses 

 in different organs, fatty degeneration of the muscles, and other 

 symptoms. Death usually takes place in from 2-2 1 days, recovery 

 being rare. The chronic form shows similar symptoms but 

 with less violence, in some cases only local abscesses ; these may 

 continue for many weeks and the bird often recovers. 



Dissection shows the presence of large numbers of a small 

 Micrococcus in the blood and abscesses, and on the intestinal 

 mucous membrane of the sick birds, and of those that have 

 died of the disease, really therefore in all parts of the body. 

 The cells of the Micrococcus, according to Kitt, are round, 

 from 0-3 to 0-5 /x in size, often united in pairs, and sometimes 

 also grouped together in larger numbers. The Micrococcus 

 has no power of locomotion, and no distinct spores have been 

 observed. 



The Micrococcus of fowl-cholera may be grown outside the 

 living bird ; according to Kitt on the usual media of cultivation, 

 gelatine, blood-serum, potatoes; according to Pasteur it de- 

 velopes with especial luxuriance in neutralised chicken-broth. A 

 supply of oxygen is necessary for its vegetation. It sinks to the 



