American Fisheries Society 391 



disease in fishes is a matter of terminology which resolves 

 itself ultimately into the question what is cancer. Cancer 

 is an ugly term not necessary to accuracy as applied to fish 

 thyroid enlargement, and may come to have an unduly 

 alarming implication in the public mind which will not 

 always suspend judgment or weigh evidence judiciously. 

 Infiltrating goiter, or still better, merely thyroid tumor are 

 better and sufficient designations in non-technical discussion 

 of this interesting disease of the salmonoids. 



It is timely to remember that in any consideration of 

 cause and effect as between fishes and cancer in man, it is 

 exactly as reasonable that the trout have acquired the 

 disease from the human race as that the transmission has 

 been in the reverse direction. If transmissible in one direc- 

 tion it probably is in the other and in that case fishes might 

 become important as a medium, or reservoir of disease. 

 But these are hardly more than speculations to which the 

 more reasonable alternative is the assumption of a common 

 cause for cancer in man and fishes. 



DISCUSSION 



Dr. B. M. Briggs, Brooklyn: Has chromium been tried? It has been 

 found useful in many cases. Have you tried arsenic? That makes the 

 mercury and iodine much more effective. 



Mr. Marsh : It has been thought to try arsenic and chromium and 

 as many elements as have an antiseptic action as soon as we have time. 



Dr. Briggs : Have you noticed in waters where iodine is present 

 that the disease is found more frequently than where the iodine is 

 absent? 



Mr. Marsh : The sea water has iodine, and this enlargement has not 

 been reported, as far as I know, in any strictly salt-water fish. The 

 fresh water has no iodine, as far as I know, except in infinitesimal 

 dilution. We had examination made of the water of a natural brook 

 used at a hatchery where tumors occurred, but we could find only one 

 part of iodine to a billion parts of water. I suppose that is negligible 

 and has no effect on the fishes. As for fresh water containing con- 

 siderable amounts of iodine, they usually occur in mineral springs. I 

 do not know of any fresh water where fish live containing much iodine. 



Mr. John W. Titcomb, Lyndonville, Vt. : The last inquirer was 

 leading to the same question I was going to ask. I wanted to ascer- 

 tain if you examined the waters where the disease was most prevalent 

 to see whether they contained any unusual chemical, or whether the 



