210 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



with the larvae of the tape-worms and other annelids, which 

 occur on the Norwegian coast in immense numbers. It is 

 stated that the surface of the sea is sometimes seen to be 

 completely covered with little worms of about the twenty- 

 fourth of an inch in length, swimming actively about by 

 means of certain hairs which encircle their bodies like a gir- 

 dle. These animals were sufficiently developed to permit 

 their identification as the young of Leucodore ciliata. Her- 

 ring and mackerel feed largely upon these animals, so that 

 the " yellow meat" consists in greater part of the fine hairs 

 which cover the exterior of the larvae in question. This kind 

 of food is considered to interfere less with the proper curing 

 of the herring, as it is much more quickly digested. 



The most objectionable kind of herring-food, however, is 

 that which is known as the "black meat," or svartaat, some- 

 times called krutaat, and occurring on the surface of the sea 

 in the form* of little granules moving freely about, but which 

 sink on being touched. This is said to be most abundant in 

 rainy seasons, when there is a short interval of fine and clear 

 weather. Herring that have fed on this substance are con- 

 sidered to be entirely unfit for salting, even when kept in the 

 nets for a much longer time than that already mentioned. 

 The salted fish has an extremely disagreeable smell, even aft- 

 er the stomach, with its contents, has been removed. 



A microscopic examination of this matter showed that it 

 consists entirely of the larval young of small shell-fish found 

 among the sea-weed, and belonging to the genus Itissoa. 

 These swim by means of two flippers covered with hairs, 

 which are protruded from a transparent shell having from 

 three to seven turns or windings. They are about one tenth 

 of an inch in length, and on being touched draw within the 

 shell and sink to the bottom. When full grown these mol- 

 lusks lose their flippers, and creep about the sea-weed by 

 means of a large foot. Thus it is easy to understand why 

 this " black meat" is more dangerous than the other kinds. 

 While the shells of the animals forming the "red meat" are 

 quite thin, and the bodies of the " yellow meat" are very soft, 

 'those of the " black meat," on the contrary, being inclosed in 

 hard shells, are not so easily reached by the digestive fluid ; 

 so that while the exterior parts, namely, the swimming flip- 

 pers, are quickly digested, the rest of the body within the 



