228 BULLETIN OF THE BUREAU OF FISHERIES. 



The above evidence proves that mussels may be carriers of typhoid fever in the 

 same way as oysters or clams if taken from waters polluted with sewage. The prob- 

 lem of protection in each case is the same. Either the sewage must be purified before it 

 is allowed to flow into waters where the shellfish are propagated or the law should forbid 

 the marketing of shellfish taken from polluted waters. Some writers have advocated 

 transplanting oysters and mussels from regions of sewage contamination to clean waters 

 for a period sufficient to allow them to be freed from any pathogenic germs. The prac- 

 ticability of this method, however, is doubtful, for as Klein (1905) has demonstrated, 

 cockles infected with typhoid organisms and thereafter kept in clean sea water frequently 

 changed allowed the bacilli to multiply, and bacilli in mussels similarly treated were still 

 plentiful after seven days. Johnstone (1909) found that mussels taken from polluted 

 beds and placed in sea water half a mile from the nearest discharging sewer were able to 

 rid themselves of 93 per cent of intestinal bacteria in four days, but that a further period 

 of eight days did little if anything to effect a further reduction. 



Wright (19 1 7) describes a type of purification tank that is being erected under the 

 supervision of the Lancashire and Western Sea Fisheries Committee in order to remove 

 as much risk as possible from the consumption of polluted mussels in Great Britain.' 1 



They are solidly built concrete structures, in several compartments, on the wooden grids of the floor 

 of which the mussels are placed, in layers not exceeding three deep. They are designed to fill over 

 the top at about high water of neap tides, when the mussels will rest under a depth of about 2 feet of 

 clean sea water. As the fecal matter is ejected, it falls through the gratings on to the cemented floor 

 beneath, which slopes away to outlet pipes of large diameter. The water is allowed to escape when the 

 tide is low, and carries, as it flows out, the excretory products. Exhaustive tests (bacteriological and 

 others) are carried out before the site of the tank is decided upon, in order to insure the purity of the 

 water gaining access to it. The shellfish remain in the structure for the space of 48 hours, and they are 

 then put into bags bearing the lead seal of the committee, to show that they have undergone treatment. 



PTOMAINES. 



Another source of danger in utilizing sea mussels for food is from the ptomaines 

 and other poisons which often occur in shellfish. The cause of prejudice which has 

 grown up against this mollusk is due to the fact that fresh mussels which exhibited 

 no signs of decomposition have on several occasions fatally poisoned groups of persons 

 who ate them at a particular time. Aurel Krause (1885), in Flinkit-Indianer, Jena, 

 reports that in 1799 a company of soldiers stopping at Peril Way, near Sitka, Alaska, 

 ate of these mollusks and that in less than two hours 100 men died in great pain. This 

 incident is doubtless the same one referred to by Dall (1870) and Petroff (1884). The 

 place and date in the two accounts are the same, but according to Dr. Dall the victims 

 were Aleut hunters from Unalaska and Kodiak instead of soldiers. It was this calamity 

 which gave the place its name of Peril (in Russian Pogibshi) Strait. In this case the 

 poisoning was supposed to have been caused by ptomaines generated in the liquor of 

 the mussels which had been exposed to the sun for a long period. The Aleuts of that 

 region informed Dr. Dall that mussels which were not exposed at low tide were always 

 safe to eat. 



* A method of purification which has been used for three years at Conway, Tn Wales, and proved to be commercially successful 

 is briefly summarized in the Fisheries Service Bulletin No. 61, June i, 1920. p. 3. "This method consists essentially in placing the 

 shellfish on wooden grids in vats of 40,000 gallons capacity, cleansing them with water from a hose, and allowing them to stand 

 in sterilized sea water for 24 hours, then cleansing with the hose again, followed by immersion in sterilized sea water for another 

 period of 24 hours, after which water containing 3 parts per 1,000,000 of available chlorine is run over the shellfish and allowed 

 to stand 1 hour. The shellfish are shipped in sterilized sealed bags." 



