Clvii. the Liberation of Methyl Sulphide by Seaweed

THE smell given off from seaweed is of two kinds-that associated with decomposing weed and that evolved by the weed in its natural condition. It is the smell of decomposing weed which is usually the more noticeable by the seaside, being characterised as a rule by a more or less distinct odour ofhydrogen sulphide which arises in part, presumably, from the putrefactive reduction of the organically combined sulphates which form a marked characteristic of so many marine algae [Haas, 1921; Haas and Russell-Wells, 1923]. There do not appear to be any recorded observations on the nature of volatile odoriferous principles given off by undecompo'sed seaweed, and it is with this aspect of the question that the present communication deals. The immediate incentive for this investigation was the peculiarly penetrating, somewhat sickly odour, suggestive of a volatile phosphorus compound, given off from Polysiphonia fastigiata on drying. The persistent occurrence of this smell, no matter from what locality or at what season of the year the material had been collected, suggested that the smell was due to some change inherent in the weed, associated either with the drying process or with injury due to cutting, and not to accidental contamination or to bacterial action; the latter suggestion was moreover rendered improbable by the short interval elapsing between the time of collection of the weed and the appearance of the smell. The fact that material which had been killed by immersion in boiling water no longer gave the smell suggested that the production of the smell was in some way connected with a disturbance of the normal metabolism of the plant. The investigation of this matter is reserved for a future occasion.