234 Annual Report for 1906 of Royal Veterinary College. 
are diagnosed in the Research Laboratory at the Royal 
Veterinary College, and it is quite possible that many 
outbreaks are overlooked. During the year 1905 three 
outbreaks came under observation, and that is the largest 
number that has ever been met with in one year. 
All the common breeds of domestic poultry are susceptible 
to fowl cholera, and in all of them the disease is of a deadly 
character. When once the disease breaks out it generally 
claims a number of victims every day ; and in a very short 
time, if no precautions be taken, scarcely a fowl may be left 
surviving. The duration of the illness is usually a day or two, 
during which the fowls have the plumage ruffled, show a bluish 
or livid discoloration of the comb, and suffer from diarrhoea. 
Sometimes the course of the disease is so acute that fowls 
perfectly well in the evening are found dead next morning. 
Experience shows that in outbreaks of fowl cholera, the 
owners very frequently suspect that the poultry have been 
poisoned. 
To a non-professional eye the internal organs of a fowl 
dead from this disease generally appear normal, but when the 
intestine is laid open there is nearly always more or less marked 
evidence of acute inflammation. The microscopic appearance 
of the blood, however, is of far more value for diagnosis than 
the appearance of any of the internal organs. Indeed, there are 
few diseases that can be diagnosed so readily and certainly by 
microscopic examination as fowl cholera. The cause of the 
disease is a very minute bacterium, which, at the time of death, 
is always present in such great numbers in the blood that its 
presence there can scarcely be overlooked by a bacteriologist. 
As the disease is highly contagious, being spread by the 
faeces of affected birds, and the course of the disease is rapid, 
it is of the utmost importance to make an early diagnosis. 
When the existence of the disease has been established, all 
the fowls showing any symptoms of infection ought to be 
destroyed or isolated, and the remainder should be moved 
to fresh premises, or, if the season of the year permits, penned 
on fresh ground, which ought to be changed from day to day 
until at least a week lias elapsed without a fresh case. 
Where a complete history is obtainable, it is generally 
possible to trace outbreaks of fowl cholera to the recent 
purchase of an infected fowl, but sometimes the occurrence 
cannot be accounted for in this way, and it appears not 
impossible that the disease is occasionally sporadic. 
Psorospermosis. 
Psorospermosis and coccidiosis are the names applied to 
diseased conditions caused by certain microscopic animal 
