6 BULLETIN" 217, U. S. DEPARTMENT OF AGRICULTURE. 



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. 





