122 American Fisheries Society 



are, as a rule, able to resist the digestive juices of but a lim- 

 ited number of closely related species, in some cases, of but a 

 single species to which they have become adapted. From 

 this generalization comes the comforting thought that, even 

 i f we had not acquired the habit of cooking our food, which 

 effectually puts a stop to any possible infection from en- 

 cysted cestodes, the chances that a larva, which is known to 

 become adult only in the winter skate, or in a single species 

 of shark, should find congenial soil in the alimentary canal 

 of a warm-blooded mammal, are too remote for even mo- 

 mentary consideration. In other words, animals, and among 

 them we may include man, are naturally immune with re- 

 spect to a large number of parasitic forms that undoubtedly 

 from time to time find their way into the stomachs of the 

 eater along with the food. 



IV. PERSISTENCE OF PREJUDICE 



The difficulty attendant upon the eradication of deep- 

 rooted prejudices is well known. When the prejudice has to 

 do with food material, and is not based on individual dis- 

 likes, but affects the people as a whole, such can be driven 

 out only by fasting which merges on starvation, or by the 

 reiteration of sound reasoning backed up by experiment and 

 demonstration. Thus the splendid work of Field on the 

 mussel and on the dogfish, although entirely convincing to 

 those who with him put the matter to the test of taste, is but 

 slowly bearing fruit, and an immense source of valuable 

 food which has been unused, simply because of an unreason- 

 ing but by no means unreal prejudice, is slowly beginning 

 to find its way into our markets. 



In the interests of science it became my duty a few years 

 ago to call attention to the prevalence of a cestode parasite 

 in the flesh of an excellent food fish, the butterfish (Pri- 

 onotus triacanthus) . Since that disclosure I have found that 

 a very strong prejudice has arisen against this fish in the 

 minds of a few individuals. This result is no doubt natural, 



