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MORTALITY AMONG WATERFOWL. | | 5 
into a chalky mass which closed the anal opening. In about one- 
third of the birds kept under observation a secondary trouble de- 
veloped in the course of two days or more after they lost the power of 
flight. A watery exudate came from the eyes and nasal chamber, 
and through the internal nares ran into the throat. This occasioned 
trouble in breathing. At times the discharge thickened into a whit- 
ish, cheesy mass and cemented the eyelids together. 
THEORIES AS TO CAUSE. 
Many theories have been advanced to account for the mortality. 
It has been variously ascribed to bacterial infection, typhoid in- 
fection from the presence of sewage, parasitic nematodes, poisoning 
from the deposition of sulphur or arsenic from smelters, and waste 
water from sugar factories. Other minor hypotheses need not be 
noted. 
BACTERIAL INFECTION. 
The fact that so many species of birds are affected militates against. 
the theory of bacterial infection, and no bacillus apparently capable 
of transmitting the trouble has been isolated. Dr. J. R. Mohler, 
of the Bureau of Animal Industry, writes as follows concerning the 
ducks examined in that bureau: 
Relative to our investigations concerning the cause of death of large numbers of 
ducks in Utah, the information at hand points to the probability that death is due to’ 
an acute poisoning, and not to a disease of bacterial origin. The suggestion has fre- 
quently been made in the past that the water which the ducks drink is poisoned by 
the discharge of sulphuric acid, arsenic, copper, and other materials from smelters. 
A duck in captivity can be easily poisoned by administering any of these substances; 
but it is very doubtful whether a large body of running water in which large numbers 
of ducks in flight could obtain water could be poisoned even if a large chemical works 
discharged its entire output into the stream. Dilute sulphuric acid in small amounts 
is harmless, and it is doubtful whether ducks would drink a solution of sulphuric 
acid of any appreciable strength because of the sour taste. Estimations were made of 
the amounts of sulphates, sulphuric acid, arsenic, and copper in the stomach contents 
and tissues of ducks from Utah. In no case did the results obtained point to any of 
these substances as the probable cause of death. Small amounts of sulphates, arsenic, 
and copper can be found in the tissues of any animal, and are no indication of abnormal 
conditions. 
Practically all the live ducks forwarded to Washington for study promptly recovered, 
while the dead ducks received were autopsied, but failed to show lesions of diagnostic 
value. Numerous inoculations were made from the different organs of the ducks, both 
on culture media and into experimental animals, but up to the present no special 
organism has been found which might be regarded as the causative agent of the disease. 
The earlier incrimination of the coccidia found in the intestinal canal of a number of 
_ ducks, as the exciting factors of the disease, has not been substantiated by later 
investigations. 
PARASITIC NEMATODES. 
Microscopic examinations in the field of a large number of blood 
smears failed to reveal the presence of nematodes, and a collection of 
material from the feeding grounds of the ducks near the mouth of the 
