REPORT OF THE COMMISSIONER OF FISHERIES. 49 
a degeneration of the muscle tissue. As soon as it is possible to do 
so, the Bureau will undertake a more extensive investigation in the 
field in order to learn the distribution of the parasite, the conditions 
that bring about its occasional increase in abundance, and any pos- 
sible method of remedy or control. 
The cooperative work with the State Geological and Natural 
History Survey of Wisconsin in an inquiry into the biological and 
hysical conditions of life in inclosed waters has been continued. 
rogress has been made upon the reports of investigations of Lake 
Champlain and those of the lakes of Washington and Idaho. 
In response to a widespread interest in the subject of frog culture, 
evidenced by the daily receipt of inquiries for information and 
advice in the matter, there is in preparation a report dealing with 
the natural history of frogs. Field studies are also being conducted. 
An interesting test was made in connection with an experiment in 
rearing fresh-water mussels at the Fairport station. While the 
commercial mussels are native to rivers and not to still waters, some 
fishes which had been infected with the glochidia of mussels in the 
way ordinarily followed in practical operations were subsequently 
retained in floating crates and others were placed in station ponds. 
After two seasons of growth it was found possible to cut and finish 
buttons from the shells of these artificially propagated mussels. 
The rate of growth was much more rapid than had been expected. 
It is not assumed that mussels can be reared commercially in such 
waters, but the experiment is of interest and value as throwing 
light upon the nature of the results to be expected from the practical 
operation in public waters. ; 
While the Federal Government exercises no jurisdiction over the 
pollutions of waters as affecting fisheries, the Bureau can render a 
very practical service in the investigation of reported cases of pol- 
lution where the importance of the stream and the alleged extent 
of the damage done is such as to warrant its taking cognizance of 
the matter. In some instances the reports are found to be without 
due foundation, while the agencies complained of are exercising all 
proper care. A report of the actual facts based upon a careful 
and unprejudiced examination of conditions serves to allay suspi- 
cions and prevent the further existence of dissatisfaction. In other 
cases the conditions are observed to be as alleged, but abatement is 
effected through a clear and convincing presentation of the facts to 
the offending parties, coupled with suggestions as to practical reme- 
dies and an appeal for cooperation. Again, there may be encoun- 
tered those who are carelessly permitting industrial wastes to render 
a stream uninhabitable for the more desirable fishes and who are 
not amenable to reasonable suggestions. In such cases the findings 
of the Bureau can still serve a useful purpose in directing public 
attention to a wanton abuse and in reinforcing those who may be 
interested to seek relief by process of law. The Bureau has within 
tne year conducted a number of investigations of this kind and the 
reports have been placed as promptly as possible in the hands of 
the parties interested. 
