GATTY MARINE LABORATORY, ST ANDREWS. I I I 



9. On the Attacks of Helix aspersa on young- Sycamores 

 at the Gatty Marine Laboratory, St Andrews. 



By Prof. M'Lntosh. 



For many years, indeed since 1896, it has been somewhat 

 difficult to get shelter at the Gatty Marine Laboratory, which is 

 exposed to every wind that blows, especially from the east and 

 north-east. The site is on pure sand on an eastern beach. A 

 line of about a dozen sycamores was at once put in on the 

 western side, and a line of elders along the eastern edge. As 

 soon as the sycamores came into leaf in June a cold briny wind 

 from the east or north-east, followed by sunshine, caused the 

 leaves to shrivel, and most of the trees perished. This happened 

 so frequently that it was thought best to let the various shoots 

 from the roots grow up so as to make a kind of bush or copse, 

 and this proved successful, though a considerable gap yet exists 

 at the north. Year after year, by the kindness of Mr George 

 Bruce, young sycamores (from 3 to 6 feet) from his belt at the 

 side of the Kinness Burn have been planted in the gap, and 

 almost as constantly have they perished — like most of the 

 elders on the eastern border, the places of these having been 

 successfully occupied, after various experiments, with Olearia 

 Hastii. For some years the Laboratory has been closed and 

 the grass and other herbage allowed to grow, so that the snails, 

 which were always abundant and were constantly eaten by the 

 thrushes and blackbirds, flourished more than usual. On 

 returning to the Laboratory in May (1924) I was struck by the 

 appearance of the bark of the young sycamores last planted, 

 which seemed to be dead, for it was different from the 

 scaling caused by decay, and the pale patches often showed 

 smoothly rounded and bevelled edges to which the bark 

 tenaciously adhered, and these were evidently caused by the 

 rasping action of some organ like a snail's odontophore. The 

 patches were not confined to the base of the stem, but also 

 occurred a foot or two up, and frequently on the southern 

 aspect of the trees. In a few instances the healthy shoots 

 growing from the roots of sycamores had also been damaged. 

 No interference had happened in the case of sea-buckthorns or 

 Olearia^ but a few of the elders seemed to have been injured. 

 On searching the trees several examples of Helix aspersa were 

 found still adhering to the patches on the stems in sheltered 



