266 BACTERIA IN OTHER FOODS 



trays above it. In the top tray mussels were also placed. Some of 

 the fish were spread out and others heaped up. The results were : 

 Ten minutes mussels pronounced spoilt, and useless to the trade ; 

 cockles " all right " in upper layers, but the bottom layer overcooked. 

 Five minutes mussels " all right," and cockles better than the ten 

 minutes' batch ; the upper layers " could not be better " in appear- 

 ance and flavour, but the bottom layer was again pronounced 

 somewhat overcooked, or at any rate less satisfactory than the 

 others. No doubt the steam was hotter at the bottom of the vessel 

 and the exposure greater. The bacterial results were as follows : 

 The cockles were found to be sterile in all cases : the mussels were 

 also found to be sterile, except in the case of those placed in heap on 

 the top layer and steamed for five minutes. Some of these still 

 retained living spores. It is probable that if exposed to the more 

 direct action of the steam even the heaped mussels would be 

 completely sterilised by five minutes' cooking, without impairing 

 their trade value. As a result of these experiments the Fish- 

 mongers' Company was reported as recommending to the trade the 

 substitution of steaming for boiling. 



Many other similar foods have been implicated in the spread of 

 disease. Dr Hamer investigated outbreaks of typhoid fever in 

 London in 1900 and 1903, in which he showed the extreme prob- 

 ability of fried fish acting as the Vehicle of infection.* In 1900 Dr 

 Plowright traced similar infection in thirty persons to polluted 

 clams, shell-fish comparatively little known in this country as an 

 article of diet.f Derived from sewage-polluted layings, clams may 

 readily become contaminated, and if uncooked may convey disease to 

 the consumer. 



* Ninth Annual Report of Medical Officer of Health of Administrative County of 

 London, 1900, p. 37, and Appendix; and Special Report, No. 719, issued 1904. 



f The clam is a shell-fish comparatively little known in this country as an 

 article of diet except to the dwellers near those of our coasts on which it occurs. 

 Belonging to the Siphonidae division of the Conchiferse, the clam (My a arenaria'), 

 like its ally the cockle, is found abundantly round our shores. It has, however, a 

 wider geographical distribution, being found in the Arctic Regions, where it con- 

 stitutes an important article of food. In America it is largely consumed in Boston 

 and along the Massachusetts seaboard. The clam of New York is a different species 

 (Venus marcenaria). It has a remarkably developed syphon, the inhalant and 

 exhalent tubes being joined into a trunk-like body 3 or 4 inches in length, which the 

 animal protrudes in an upward direction towards the surface of the mud. The clam 

 itself lies buried in the mud, into which it has worked itself by the aid of its muscular 

 foot to a depth varying from 8 to 18 inches. The currents of water passing in and 

 out the syphon keep open the vertical burrow the creature has made, while the 

 surface of the mud is covered by the tide, but where this recedes and the mud 

 becomes dry, the position of the clam is shown by a small round depression on the 

 surface. In Great Britain it is regarded as a kind of inferior oyster, and like the 

 last-named is preferred uncooked by those persons who are really fond of it and to 

 whom it is a luxury. More generally, clams are cooked by having boiling water 

 poured over them, and being allowed to remain in it until the shells open. 



