SEA MUSSEL MYTILUS EDULIS. 227 



parts of the body pervaded with genital tissue (fig. 21S). An idea of the relative food 

 values of a mussel before and after soawning is shown in a most striking manner by com- 

 paring figures 214 and 218. 



WHEN MUSSELS ARE UNFIT FOR FOOD. 



While advocating the use of mussels for food, the author has often encountered 

 persons who protest against so using them on the ground that they are a dangerous 

 product which can never be eaten with safety. But having eaten them for years himself 

 and knowing many other persons who have been doing the same thing without ever 

 experiencing disagreeable symptoms, the author is convinced that the idea of their 

 possessing any poisonous qualities is false. However, to say that they are never poison- 

 ous would be as wrong as to say that oysters, clams, or lobsters are never toxic. When 

 infected with disease-producing germs, ptomaines, or other injurious substances any of 

 these shellfish are a menace to human life if ingested; and the record of suffering and 

 fatalities which appears in the medical journals and daily papers serves to show how 

 important it is to select these foods with care. A study of mussels as a human food 

 shows that they are a most wholesome shellfish and that they are no more dangerous to 

 eat than are oysters, clams, or lobsters, provided the same care is used in selecting them. 



The purpose of this section is to show the causes and symptoms of poisoning which 

 have resulted from eating unwholesome mussels, with the hope that similar occurrences 

 may be averted in the future. The subject may be considered under two heads— diseases 

 resulting from eating mussels taken from polluted waters, and diseases resulting from 

 ingesting poisonous substances secreted in the body of the mussel itself 



MUSSELS AND TYPHOID FEVER. 



Ruchan (19 10) collected some very important data on the relation of mussels from 

 polluted waters to typhoid fever. The results of his paper are based on evidence col- 

 lected at Birmingham, England, between June i, 1904, and June 1, 1909, during which 

 period there were 855 cases of typhoid fever, of which 124, or 14.5 per cent, were attrib- 

 uted as due most probably to mussels and 32 to other shellfish. 



Investigations demonstrated that several of the sources from which mussels were 

 supplied to Birmingham were polluted with sewage. Bacteriological examinations of 

 mussels taken from the Birmingham market showed that the number of microorganisms 

 to a single mussel varied from 2,000,000 to 1,000,000,000. The most common number 

 was between 10,000,000 and 100,000,000 per mussel, which is considered high. Where 

 the number reaches 1,000,000,000 it undoubtedly indicates gross pollution. In 5 sam- 

 ples the Bacillus coli communis was actually isolated, while evidence of its presence 

 was found in 26 other cases. Since the Bacillus coli communis is so closely associated 

 with the Bacillus typhosus it is reasonable to infer that the presence of this germ in mus- 

 sels means the possible and probable pollution by the typhoid bacillus. Sewage pol- 

 lution was also indicated by the presence in large numbers of the Bacillus enteriiides 

 sporogcnes and of numerous streptococci. The investigations of Johnstone (1912) further 

 show that there is abundant epidemiological evidence that enteric fever has been trans- 

 mitted by mussels. 



