56 Proceedings of Royal Society of Edinburgh. [sess. 
the tube walls, and any dissolving out or excavation of the whole 
tube and of its contents, by some subsequent exposure to solvent 
agencies, such as exposure to sea water, or from mechanical violence 
deforming, and more or less crushing the tubes out of all distinct 
recognition. One lasting effect, it would seem, is likely to remain, and 
that is the removal of the finer particles from among the coarser for 
some little space round the original path of the worm. The effect of 
this would he to leave a change of texture along that path — a coarser, 
rougher graining in the sand in any slits or hollows along which 
the original tubing has been made. 
We have not yet done, however, with the lessons to be learned 
from a careful examination of our living annelids. Hitherto I have 
been drawing from a few facts reported by others as to the work of 
annelids, certain conclusions as to consequences which that work 
would probably or necessarily involve. But as I recollected one day 
that I was writing this paper within 200 yards of abundant shore 
worms, I determined to make some experiments and some further 
observations on what they do. The very first thing I found was 
that, although the orifice of the tubes as they are opened on the 
surface are roughly and irregularly cylindrical, yet the slightest 
pressure on the sand, such as even a sharp knife produces in 
carefully cutting off the castings, is sufficient to draw or deform the 
orifice out of its true shape, and to convert it into an oval aperture 
or ring, or even into a mere slit. Further, I have found that the 
path of the worms, although generally vertical for a short distance 
below the surface, does not generally continue to be vertical, but 
soon becomes sloping, and often almost or altogether horizontal ; 
consequently any section of the sand is sure to cut the tubes at 
various angles, and therefore to exhibit them variously as ovals, 
or as circular rings, or as hollow lines. In order to test this, I 
have used an expedient which has been highly successful. I have 
had a trench cut deeply round a group of worm castings until 
the block of sand containing them has been isolated like the stump 
of a tree. This block has then been undercut horizontally and 
lifted out of the shore. Then carefully opening the orifices of the 
burrows, I have injected, with a syringe, liquid plaster-of-paris. 
The easy and complete passage of this injection proves how 
completely the path of the worm is kept open by the agglutination of 
