26 American Fisheries Society 



August 6, 1913, one nematode was found in the flesh of 

 the side of a butterfish. It was 29 millimeters in length, 

 much larger than those found on the viscera. 



On July 14, 1915, one nematode was found in the flesh 

 of a butterfish. The fish had been opened by another 

 worker in the laboratory and had been lying for some 

 time before I examined it. The length was 29 milli- 

 meters. It is a different species from that which is 

 found on the viscera. Another nematode of the same 

 species as the last was found in the flesh of the side of 

 a butterfish on July 14, 1915. It was 32 millimeters in 

 length. 



These three nematodes make up the total found in the 

 flesh of the butterfish to date. In each case they would 

 have been detected without much doubt if the fish had 

 been split open in preparation for the table. This record 

 of three nematodes found in three butterfish out of nearly 

 6,000 butterfish examined especially for flesh parasites 

 over a series of years is a very remarkable one. Very 

 few of the species of animals used for food can show 

 such a favorable record after having been subjected to 

 such a rigorous test. 



The occurrence of immature, encapsulated nematodes 

 on the viscera, and especially on and among the pyloric 

 caeca of the butterfish is common, but in this the butter- 

 fish is not exceptional. About 20% of the butterfish that 

 I have examined this season have had many of these 

 nematodes on the viscera; about 40% had none; the re- 

 maining 40% had few, often only one or two were found 

 after very careful search. Fish were left unopened from 

 one day to the next, and variously tested to see if the 

 nematodes on the viscera showed any tendency to enter 

 the flesh. None did so. 



That there is nothing new or exceptional in the occur- 

 rence of nematodes on the viscera of butterfish is abund- 

 antly proved by records made in previous years. For 

 example, in the Bulletin of the U. S. Fish Commission 

 for 1899, p. 279, under the butterfish the following state- 

 ment is made : 



