FOWL PLAGUE 83 
fowls was possible by subcutaneous injection of portions of cerebral 
substance. It was not possible to infect domesticated ducks with 
wild duck virus in doses however large, and administered by intra- 
venous inoculation, ingestion, intracerebral inoculation or instilla- 
tion into the conjunctive. 
Symptoms. The incubation period is usually 3 to.5 days, but 
exceptionally 2 days or even 7 days. It is much shorter when birds 
are inoculated. The symptoms greatly resemble those of fowl chol- 
era. Death may occur while the bird is on the roost or on the nest 
without its having previously exhibited symptoms. 
There is an acute type of the disease in which the bird lives at 
the most: three or four days. In a subacute form the birds survive 
7 or 8 days. Recovery practically never occurs. 
In the acute type, the first noticeable symptom is inappetence. 
Then the bird declines into a condition of weakness and somnolence, 
hides in corners, becomes indifferent to surroundings, with half 
closed eyes, drooping comb, and ruffled feathers. The temperature 
rises to 110° or 112° F., but may drop to subnormal before death. 
The comb commonly takes on a violet color which proceeds from the 
borders, or spots form on the sides, but it soon appears black. In 
some cases the comb is covered with white scales. The bird gen- 
erally dies quietly in a somnolent condition, which is only occa- 
sionally interrupted by spasms. 
In the subacute form which occurs quite frequently in cases of 
natural infection, the bird ceases to eat and drink, and goes on 
the nest for protection from the light. The general appearance is 
deceptive as indicative of the diseased condition. Upon investiga- 
tion and when an effort is made to see the bird walk, it may not 
rise to the feet, or moves the feet with difficulty, staggers, with the 
head wabbling and turned backwards which attitude appears to be 
involuntary. With the development of the disease, paresis occurs 
and stupor becomes deeper. In some cases in this stage a viscid 
secretion flows from the nostrils and mouth or the material may be 
squeezed from the nostrils. A diphtheritic type has been observed, 
in which fibrinous exudate occurs in the nasal, oral and pharyngeal 
cavities. Conjunctivitis and lachrymation may occur. 
As a rule there is no diarrhea. The feces are quite solid, often 
green in color and of the usual amount. In the later stages of the 
disease some birds discharge hardly any feces. At death and after, 
a fluid is discharged from the cloaca and beak. 
Morbid anatomy. Freese has conducted numerous autopsies 
