American Fisheries Society. 71 
the number of other fish, but he thinks that the other fish were 
afraid of the carp for a while but now they seem to grow together 
just as other fish do; that the carp do not fight them any more 
and that the other fish are increasing, and this year their catch 
has been the best they have had for a number of years, in the 
vicinity of Spring Lake. 
Dr. Bean: |! do not hke to prolong this discussion, but the 
subject is one of so great importance to fish culturists that I 
would like to say just a word. I understand that the paper deals 
mainly with propagation and protection, but the associated 
question of pollution is one so near to the results at which the 
fish culturists aim, that we cannot consider the two without also ° 
mentioning the third. 
President: That would probably come under the head of 
protection from pollution anyhow. 
Dr. Bean: It appears to me that that is one of the most im- 
portant subjects with which we have to deal at the present time, 
not only on the part of the federal and state governments but on 
the part of the private fish culturist as well. To illustrate how 
destructive the matter of pollution may become (and the instance 
which I have in mind is a thing which has been observed in Ger- 
many and reported upon by an eminent bacteriologist, Dr. 
Hofer), I would like to refer to the washings from manure heaps 
and pig-sties and other domestic arrangements which are turned 
into streams supplying trout ponds. That kind of pollution, 
according to the researches of Hofer and others, has caused the 
disease which we -have recognized in our own country only too 
seriously in fact, as the boil or ulcer disease, especially among 
the brown trout, and to some extent among the brook trout of 
this country. Prof. Hofer had brook trout suffering from this 
disease under observation in Germany, and his paper relates to 
ulcer disease among brown trout mainly, but also among brook 
trout. Now this very source of pollution has, in one state, to my 
own knowledge, reduced the stock of one particular species of 
trout from some hundreds of thousands to a few thousand in a 
very short time. It is a very serious matter then for us to con- 
sider and I do not believe that it has received the attention from 
the states and the federal government to which it is entitled, up 
