On some Factors Limiting the Habitat of Arenicola marina

SUMMARY In the foregoing work it was found that: Arenicola marina was repelled and could not burrow in sand containing 20% of ferric oxide in the amorphous state. That 0·021% ferric oxide in suspension in sea-water was lethal owing to its forming with the mucus of the organism an envelope which prevented contact with the surrounding air-carrying water. That calcium carbonate, magnesium carbonate, Stourbridge clay, kaolin, and kieselguhr had the same effect as the ferric oxide in suspension. That although able to live for a short time in water of salinity 3·10%‰, Arenicola marina tended to become so turgid in water of 14·32%‰ as to be unable to burrow.