Mr. Alex Wetmore - 2. 
specimens of the mud sent in without treatment, with a view if possible of 
finding living nematodes. Perhaps the easiest way for you to do this is to 
collect some of the aquatic plants and sprinkle them well with the ooze, and 
forward in a stout box; provided the vegetation keeps moist, the nematodes 
will live in the mud and ooze attached to the plants. . 
Doctor Cobb also suggests that it might be well for you to examine 
the blood of affected ducks under a moderate power objective - say one-sixth - 
with a view of determining whether the ducks carry nematodes in the larval 
state in their blood. These, when alive, are sufficiently mobile to make 
their detection very easy provided they exist in sufficient numbers to be 
of pathologic interest. I fear it may be too late to make this last test, 
but it is possible that there are still enough affected ducks for the ex- 
periment. 
Broadly speaking, the ducks of the Salt Lake Valley may be divided 
into two great groups - those which are reared in the marshes about the Lake 
and the vicinity, and the migrants. As a result of your observations, are 
you sure that the diseased ducks include the individuals reared in the locality? 
I presume there is no doubt that they do. Secondly, as a result of your ob- 
servations, can you tell how soon after migrants appear in the locality 
they are affected by the disease? Any information tending to throw light on 
this subject will be of interest. 
The recipe for the solution to preserve the material is enclosed. 
