10 BULLETIN 672, U. S. DEPARTMENT OF AGRICULTURE. 
under observation the nictitating membrane was enormously swollen 
and irritated, so that it distended both upper and lower lids and cov- 
ered the whole eyeball except a small portion at the posterior corner. 
The alimentary tract is found to be practically empty. The intes- 
tine is shrunken, firm, and hard to the touch, and much reddened, 
and on slitting and examining it closely the lining appears more or 
less irritated. The irritation is most marked in the first (duodenal) 
loop below the stomach, but may extend through the length of the 
small intestine as far as the caeca. This reddening of the lining of the 
canal appears sometimes in spots or patches or sometimes is contin- 
uous. Areas of irritation usually seem most severe at bends in the 
intestine. The gut contains a small quantity of mucouslike matter 
that is yellowish in color, and usually has flecks and clots of blood in 
it from ruptured capillaries. Ordinarily considerable gas is present. 
There is marked sloughing of the inner lining of the intestinal walls. 
Sometimes the blood content in the intestine is so large that the con- 
tained fluid is blackened. The caeca (in species having the caeca well 
developed) usually contain masses of broken-down and partly digested 
blood. The stomach lining between the lower end of the proventric- 
ulus and the hard grinding pads of the ventriculus is often softened 
and tends to slough. As digestion in birds is rapid, the stomach is 
soon empty of food and retains only gravel or hard seeds of the potato 
moss (Potamogeton pectinatus) and rush (Scirpus paludosus) . 
Other organs of the body appear normal. The ventricles of the 
heart are found to be in systole. The blood has a tendency to remain 
fluid, a condition sometimes holding for 10 or 12 hours or more after 
death. 
The feces are loose and watery, more or less greenish, and are 
voided at frequent intervals. In helpless birds the feathers about the 
vent become dirty, and often the feathers covering the entire posterior 
portion of the lower surface of the body are stained green. The 
sphincter muscle closing the anal opening is relaxed, and little or no 
fluid is retained by the cloaca. The mucous membranes of the anus 
are irritated. As ducks sicken rapidly, when first affected they are 
usually very fat, and if the attack is not immediately fatal they sub- 
sist on this stored-up energy. Therefore, after two days the ordure 
shows a marked increase in the white matter thrown off by the 
kidneys. Ultimately this constitutes almost the entire excrement. 
As the renal matter is almost solid, it often clogs the cloaca and, com- 
pacting in a hardened mass, closes the anal opening entirely. These 
indurated masses are acid in their nature and serve still further to 
irritate the mucous membrane of the cloaca. 
Among the species of ducks affected the green-winged teal has the 
least resistance to the malady. Field observations have shown that 
these teal may become severely affected in from 6 to 12 hours. The 
