208 
PROCEEDINGS OF THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
but Western Perthshire depends rather for its rainfall on 
the passage of the main stream of depressions which come 
from the Atlantic, and pass over towards Norway to the 
north of us, and experience shows that the rain from this 
source may always be trusted to be copious. 
Dr Buchanan White, in moving a vote of thanks to 
Mr Campbell for his paper, remarked that it would be 
very desirable to publish in the Society’s “Proceedings” 
each year a summary of meteorological observations in 
the county, and also a statement of the forwardness or 
lateness of the season in regard to vegetation. 
Mr Campbell agreed to undertake the compilation of 
such a record, and the matter was remitted to the Council 
for further consideration. 
2. “ On Some Fresh-Water Annelids." By Professor Allen 
Harker, P.L.S., Royal Agricultural College, Ciren¬ 
cester, Corresponding Member. 
On our dry oolitic Cotteswold Hills we have very few 
running streams, and our farmers depend for a supply of 
water for their stock on pools dug in the soft cream- 
coloured stone, in which the rain water accumulates. 
These pools are capital collecting grounds for the student 
of the indigenous invertebrate animals, as well as of the 
fresh-water algce, and since every field (or at least every 
two or three fields) has a common pond, the collector has 
never far to go to reach his hunting - ground. One 
phenomenon that invariably attracts the attention of my 
students, and furnishes us with a subject for a half-hour’s 
talk, is that exhibited by the presence in those pools of an 
innumerable concourse of one fresh-water annelid, the 
little red worm, probably the Tubifex rivulorum of 
Lamarck. I have sent a diagram with a much-magnified 
drawing of the creature, side by side with some details of 
its anatomy. Owing to its habit of living in the mud at 
the bottoms of ponds and streams, at a depth which 
ranges within very narrow limits, it is always distributed 
in our pools so as to form a ring right round the pool, at 
about (generally) a foot from the edge of the water. The 
ring itself is often not more than from 1 to 2 inches in 
thickness. I don’t know that this fact of its existing only 
at a certain depth has ever been described before. But it 
is worth recording, and that it is due to some conditions 
affecting the animal is certain, because in chance pools 
left by a prolonged period of high rainfall, where the 
depth of the pool is the same all over, the whole of the 
surface of the mud at the bottom will be occupied by the 
annelids, while, on the other hand, where the bottom 
gently shelves down to a considerable depth, as in our 
artificially-formed pools, they are rigidly confined to a 
concentric area of narrow width. 
Now the brilliant purple red colour which they have 
when seen densely massed together, shading off into a 
pink hue at each edge of the ring where they are less 
tightly packed, renders them a very conspicuous object, 
especially as seen contrasted against the soft ochrous 
colour of the mud in which they live. Add to this, 
that when you approach the edge of the pool to 
get a better view of the singularly brilliant ring of 
colour, the whole almost instantaneously fades away, 
first of all immediately opposite to you, but gradually all 
round the pond, as if by magic, and you have this singu¬ 
lar phenomenon, which never fails to cause the greattst 
astonishment when first seen. The almost instantaneous 
disappearance of the colour is of course due to the fact 
that the annelids have felt the vibration of your approach¬ 
ing feet, and taking the alarm have hastily withdrawn 
themselves from a fancied danger into the depths of the 
mud. The rate at which the vibration is communicated 
might be calculated by the speed with which the ring of 
colour disappears at the furthest side of the pond. Some¬ 
times we.amuse ourselves by approaching the pool, simul¬ 
taneously on all sides, and then at a signal all stamping 
together, when the ring disappears all at once. After an 
interval of as little as a minute, the blush of colour rises 
again on the mud, and in two or three minutes at most 
the annelids are all out again, as densely congregated as be¬ 
fore. My students have experimented with long rods 
fixed in the pond, and vibrated at a distance, but all 
their results only serve to show that the annelids are ex¬ 
tremely sensitive in the matter of touch, and bury them¬ 
selves deep in the mud on the slightest disturbance. When 
we wish to collect specimens of the worms for closer in¬ 
spection, we do not find it .quite so easy as, from their 
immense numbers, you would imagine. If we try by 
dipping a collecting bottle into the mud and then filling it, 
we find generally that we have got nothing at all but mud 
and water. The worms retreat so far into the mud that 
our bottle does not reach them. We generally take a 
deep bag-net, and drag it through the mud till it is filled. 
We carry the bag full of mud to the laboratory and put it 
into shallow dishes or tanks, covering it with two or three 
inches deep of water, and leave it for some hours to settle 
to clearness. We then find that the worms have accom¬ 
modated themselves to their new position, and are waving 
their bodies from side to side,—the anterior half protrud¬ 
ing from the surface of the mud, the posterior buried in it. 
In our laboratory tanks we can repeat all the experiments 
made on a larger scale by the side of the pond. For ex- 
