6 BULLETIN 217, U. S. DEPARTMENT OF AGRIOULTURE. 
Weber River was forwarded to the department for study. This was 
critically examined by Dr. N. A. Cobb, of the Bureau of Plant In- 
dustry, a leading authority on nematodes, who reports as follows: 
A preliminary examination of the nematodes collected from material from the 
Weber River, Utah, does not disclose any reason for supposing any of the nematodes 
found could be connected with the great mortality noticed among wild ducks feeding 
in the locality whence I understand this material comes. A single specimen has 
been seen which is of a doubtful character and may perhaps be connected with some 
parasitic nematode form. This specimen, however, is of small importance, considering 
the large number of specimens that have been so far looked over. I think it is quite 
safe to assume that nothing in the way of an explanation of the mortality of the ducks 
will come as a result of these examinations. 
SMELTER AND FACTORY WASTE. 
Sulphur poisoning has been held by many to be at the root of the 
trouble, but the presence of ducks and other birds in California 
apparently suffering from the same disorder, in localities where there 
is no appreciable trade waste of sulphur, is sufficient to disprove 
this theory. Birds kept under experimental conditions were given 
various solutions of sulphuric acid, but they failed to show 
symptoms similar to those exhibited in nature. None of the changes 
incident to death from arsenical poison were found in the internal 
organs of the large number of birds examined. 
In regard to waste water from sugar factories on the Weber River, 
high water in the fall of 1914 came down in mid-September, carrying 
with it drainage from the settling ponds of the sugar factory, and 
though the toxic matter present was sufficient to kill large numbers 
of carp and chubs, conditions among the ducks improved immediately 
with the rush of water to the flats. 
AN ALKALINE POISON AS THE CAUSE. 
While it is not yet possible to set aside all these theories as ground- 
less, it is believed that further investigations will disclose a poison as 
the real cause of the trouble. The work of the past summer leads to 
the conclusion that the mortality results from an alkaline poison, the 
exact nature of which is still to be determined. That this is the case 
appears from several facts. 
As formerly stated, no lesions were present in any of the organs of 
the many birds examined, other than a severe irritation in the lumen 
of the intestine. Practically all the birds affected are fat, even 
though found helpless or dead; not until they begin to recover do 
they get thin. In birds relatively strong the kidneys make a vigor- 
ous effort to throw off the matter absorbed through the intestines, - 
and thus the excretion of renal matter is greatly increased and is given 
off in almost solid form. 
