On Animal and Vegetable Life in the Water of Leith. 235 
stream or of the lade harboured myriads of even this infe- 
rior type of animal life, there was hardly a specimen to be 
had, and this was doubtless due to the more rapid putre- 
scence of the deposits. Abundance of animalculse, including 
the Paramcecia, were found in the Water of Leith at all 
seasons of the year. 
One curious effect of sewage upon animal life was ob- 
served by me in the harbour of Leith. Two wooden piers 
stretch some distance into the sea ; they are constructed of 
the same kind of timber, and are of the same age. The 
west pier is not liable to be influenced by sewage passing 
down the harbour, as the tide sweeps the sewage from it, 
and the wood of this pier is nearly eaten through in some 
parts by the Teredo, a bivalve (Lamellibranchiate) mollusc, 
which is well known to be destructive to wooden erections 
in the sea. But the east pier is washed by the sewage 
water, and apparently from the disengagement of sulphuretted 
hydrogen, which is specially formed when sewage meets sea 
water, there is not a single Teredo to be seen at its work of 
drilling holes in the wood. The sewage in such circum- 
stances therefore appears to be beneficial in retarding the 
ravages of this troublesome mollusc. 
Independently of the putrefaction of the sedimentary de- 
posits, fish might live in water which contained nearly the 
proper proportion of oxygen, but the water of the Water of 
Leith from Coltbridge downwards is almost devoid of oxygen, 
and fish can no more live in water containing no oxygen 
than land animals could live in an apartment destitute of 
air. 
It is worthy of note, as evidence of the state of the Water 
of Leith, and its incapacity to support the life of fish, that 
during the summer of 1864 a shoal of young herrings at- 
tempted to enter the harbour of Leith, and those herrings 
turned over on account of the foulness of the water, and the 
majority died upon the spot. 
During the progress of these observations, attention was 
directed to a green substance consisting mainly of Euglena 
viridis, one of the Phytozoa, which was observed on the sur- 
face of the stagnating mud at the side of the Lochrin Burn, 
VOL. nr. 2 H 
